This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
Please put your theories about the PC-98 characters under the page for Touhou PC 98 Era, crossover theories under Touhou Crossovers, and predictions for future games under ZUN and move any ones you can from here to there.
Theories involving Seihou can go on its own WMG page.
Theories about Reimu or Marisa can go here.
Theories about characters from the manga can go here.
Theories about the cast of each game can go in these subpages:
Reimu really is the miko of her family's small, run-down shrine, but only in our world. With this comes an awful lot of free time and boredom around the shrine. In order to keep herself entertained, she thought up Gensokyo as a small child, as well as the characters, as something akin to imaginary friends in an imaginary setting. Perhaps influenced by real people and real events, Gensokyo, its residents, and the happenings that occur there are just as exaggerated and wacky as you might expect from the mind of a little girl with not much else to do. This would also explain the increase in complexity and refinement as the series has progressed - Reimu's grown up and thinks more clearly and in greater detail.
Perhaps Marisa is a friend of Reimu's, made after Gensokyo's initial conception, and then later playing "make-believe" together with Reimu.
This would logically explain what happened to the PC-98 characters. With so many imaginary friends, it's only natural that many would end up being forgotten or discarded. Some would be remembered in time, but most would vanish from memory.
Alternatively, Gensokyo is what happens in Reimu's mind, when she's playing with her dolls. She actually has a huge collection of victorian-dress dolls and decides to play with them, since their battles are non-lethal and it explains why everyone drinks tea after, she must've read books on Japanese folklore, every doll has a personality and it would explain the lack of men, since there are few male dolls and she's in the phase in which she must think that boys have cooties. As would say Spongebob, "Imagination!"
A bare head on a woman is considered indecent in Gensokyo.
It probably isn't as bad as e.g. going topless, but it's still probably considered somewhat rude. This would explain why virtually every character in the series wears a hat, hair-ribbon, or something else on their head. The exceptions:
Petting Zoo People with no other hats (e.g. Tewi Inaba, Yuugi Hoshiguma); this is probably justified in that they're like Felicia, who has strategically-placed fur-patches.
Kaguya Houraisan, Sara, and Yumemi Okazaki (respectively from the Moon, Makai, and the Outside) are from different worlds with separate cultures, in which this taboo doesn't exist. The same might apply to Parsee Mizuhashi; the Underground is divorced enough from the surface world that there are probably plenty of cultural differences.
Kogasa Tatara possibly hopes her umbrella will suffice. That, or she wants to surprise people with this behavior.
Yuuka Kazami is badass enough that she just plain doesn't care.
If that doesn't cut it, she's got those pajamas, complete with night cap.
Byakuren Hijiri has been sealed away for so long that she probably doesn't know that times have changed. The same can be said for Nue Houjuu.
Parsee Mizuhashi doesn't have a hat, and is therefore incredibly jealous of others.
Since her Pointy Ears have apparently ascended into canon as of Wild and Horned Hermit, Parsee may no longer need extra accessories quite as much as she thinks.
This theory really isn't all that unrealistic when you realize that some cultures actually DO state that women showing their hair is indecent. That's why they have to wear veils.
All that stuff about eating outsiders, and only outsiders? Propaganda and lies. Yukari wants Touhou to be popular outside the border, so the youkai can be strengthened by the belief of the fanbase, but she certainly doesn't want anyone going looking for the Hakurei Shrine and wandering into Gensokyo. Answer: imply that intruders will be eaten.
If this is the case, then clearly she's failed. Many a Touhou fan has expressed their desires to visit Gensokyo despite the dangers.
Youkai still eat humans.
However, they're now considered a delicacy and the number of them eaten is very low. Perfect Memento mentions that Outsiders are eaten by youkai on sight or after they've lost interest on them. They may be fair game since it won't impact the resident human population. Also, they may have struck a deal where executed criminals are turned over to a youkai who wants to celebrate or something.
Yukari eats humans by putting in them in one of her gaps.
Utsuho's another man-(and god)-eating heavyweight, as Reimu and Suika's Subterranean Animism scenario shows (some lines cut for brevity):
Suika: This is a hell raven. She's a humble bird that eats the corpses of the dead.
Reimu: She must eat mostly fried meat, then. That'll be bad for her when she's older.
Suika: But, it looks like she's eaten something pretty bad.
Utsuho: What are you mumbling on about? Did you come on a trip here to get eaten?
Suika: I can feel something that doesn't belong in hell. She's ... Probably eaten a god.
Utsuho: See, your body's getting burned up pretty nicely now. I want to eat you up right now, but it's not good to rush. You have to let it fry just the right amount for it to taste the best.
This considered, Rumia's probably one of the nicer humanitarians in the series, since she asked politely first.
Counterpoint: While youkai can eat humans, in Gensokyo it can generally lead to dramatically shortened lifespans. For one thing, there is the presence of Reimu, who has "youkai extermination" in her job description and is the main character. More importantly, however, is the idea that there are quite a few powerful youkai who live away from humans and want to be left alone and would not hesitate to put an insolent youkai in their place if they do anything to bring attention to them. Even Yukari, for all of her laziness, would be very quick to put an end to something that could threaten the peaceful stability of Gensokyo. If you don't believe, just ask Tenshi.
Not to mention, the humans of Gensokyo are mostly descended from youkai hunters, meaning that most of them have at least some degree of magical power. Thus, a run-of-the-mill weak youkai (bear in mind that even the Team 9 members are stronger than the average youkai) would be in for more of a challenge than you might think if they try to eat a human.
The current line of thought is they don't eat Gensokyou natives; but they are periodically consuming humans from the other side. Reimu did explain that the Wall isn't a prison; and the zashiki-warashi were able to travel to and from easily enough.
Look at it like this: Rinnosuke has firmly established that, if there is sufficient active disbelief in a given phenomenon — in his words, it is considered to be "illusory" — it is at least capable of existing in Gensokyo. Meanwhile, the outside world is a patriarchal society: the idea of women calling the shots is tenuous at best. The idea of a non-adult woman being in a position of power is even more "illusory." Thus, in Gensokyo, the land of illusion, just about everyone of any importance whatsoever is female, and on top of that, very few of them look entirely grown up. In fact, it seems that lately (i.e. from the first Windows game on), the only reason any male characters are significant is because they are male and we hear about them. This allows for Schoolgirl Lesbians, as well.
His theory is nowhere near as firmly established as some would like to believe. Too many things from the outside world, which decidedly do not depend on belief to exist, show up in Gensokyo—for example, outside humans who get lost in Gensokyo (not just abductees), and many of the items Rinnosuke's shop. That was part of the counterexamples from the main page; too many of Rinnosuke's curios are electronics which were current-generation (such as the Apple iPod) at the time of their discovery (with the exception of things like the Nintendo Gameboy). To be honest, Rinnosuke's theory may as well be Wild Mass Guessingof his own.
That said, outside of the obvious out-of-character explanation that the Lady Land is Author Appeal, males are known to exist in significant qualities in Gensokyo—they just aren't given the spotlight (with Rinnosuke, Unzan, and Genji being the exceptions as of this edit).
Gensoukyou split off during the Meiji era, and has mostly stayed there technologically. The games are set roughly at the time of their release.
Perhaps the modern technology passed through Gensoukyo's border, or Reimu found it in her donation box. Canonically, the borders aren't as foolproof as they should be - Yukari's never fixed the hole Yuyuko formed in PCB, and Maribel can get through the border, as others possibly could.
If things exist in Gensokyo due to people not believing in them, things such as the Game Boy and iPod were items that were lost by someone in the real world, and the owner stopped believing they'd ever find it again. Which would mean there has to be an awful lot of odd socks in Gensokyo...
I blame Yukari.
A lot of characters can equal or outmatch Yukari's "Omnipotence".
Remilia, she can manipulate fate, that means, she could theoretically decide what will happen. ANYTHING. She could decide, that Yukari would just relax and the next second * BAM* dead. And if someone is plotting up something against her, she could manipulate fate, that he will never succeced, or even better: Manipulate fate that no-one is standing up against her while conquering the very existence on cruise control.
Kaguya, she can do pretty much the same thing than Remilia, but on a diffrent way. Her ability allows her to let stuff last eternal (aka. Time Stands Still) or she can cause things to happen at an instant. The theory of Singularity says, everything happens somewhen, you just have to wait enough. Kaguya doesn't have to wait.
Ex-Keine. Being able to alter History is pretty badass, but History isn't just past, it's also FUTURE! That means, Keine is ridiculously powerful, since it's basiclly the Ability of Remilia, with the bonus that she can alter things that already happened. (You say that she can do that only while Fullmoon? She changes History, so that there is always fullmoon!)
Hina, yes, she can apply every curse on someone she wants. This implies eg. "Imperius" of Harry Potter. A curse which causes the cursed person to lose it's will and that person will only do the bidding of the one, who layed the curse upon it (in this case Hina). So she has omnipotence by forcing another Omnipotent being to do what she wants.
Yuyuko. Her ability is to induce death. That's it. She doesn't even have to snap her fingers, she just wills it and you're dead. Naturally, this wouldn't work on Kaguya, but she would be able to take out any of her other opponents.
As pointed out further down the page, Yuugi, who was explicitly holding back the only time we've seen her to now, has the "Power to control supernatural phenomena". That may mean she can just say "Oh, you want to alter my fate/rewrite my history/will me out of existence? Well I say that's not going to happen. What now?" In the end, though, I think what we end up with is a high noon standoff—with all these godly reality-bending powers, whoever shoots first will win. This probably makes for some very paranoid people at the top of the power chain.
Except that the powers aren't absolute. If they were, practically every character would break the scale. Yukari couldn't gap to the moon, she had to wait for specific conditions. Satori can't read people's thoughts if they're too far away. Yuyuko can't kill people who are immortal, Cirno can't freeze the nuclear furnace, Remilia's skill is implied to be tied to name-fortunes, meaning Yukari would have to accept a new name to get fate-changed, and even then it's a general fate, not a "you die in two seconds from X" deal. It's plausible that abilities flat out fail if contested against a stronger being- Yukari saw through Keine's history-hiding and ignored Suika's gathering, for example. Finally, the only (I think) specific canonical instance of one ability going against another was the last phase of the Kaguya fight, where she tries to break the eternal night enchantment. If abilities were absolute, she'd just be able to manipulate eternity to break it instantly. Instead she has to distract the protagonists with a barrage and break it in bits while they're recovering.
Basically, Yukari is considered above the others because she's the only character who has used her abilities to more than the most basic degree, regularly, and has a wide-ranging ability to begin with. Remi, Keine and Yuugi would probably be in the same boat if their powers were shown to be as wide ranging.
The Touhous are substantially less powerful than the games suggest.
This is my oft-trumped WMG, so I might as well plant this mutha here for safekeeping. The idea is this: all the characters' assorted useless-sounding superpowers, with the handful of really unspeakably stupidly powerful ones, work just as described and no further up or down the power scale. Danmaku is in fact a separate magical skill used to solve problems or blow off steam in a violent-feeling but non-violent fashion; skill at danmaku is independent of one's innate mystic powers. The 'Soak is not merely a place for monsters and such to hang out, but a sort of nature reserve to keep those too weird to live and too rare to die from getting steamrolled by superstition or the march of progress, as well as segregating the truly terrifying from a world where they would do the most bad.
It is fortunate that so far all the big nasties have consented to fight using the harmless-but-flashy danmaku style, because otherwise all sorts of planetary holocausts could've gone down by now—Reimu is a tough little bitch, but that can only take her so far against an uncontrolled threat.
Reimu can still fly away from reality and watch as stuff passes through her while wiping her enemy out. She's still so broken.
Now. When you say "The Touhous" I read "A few of the Touhous". Suppose Danmaku was indeed harmless (and it's not, because no matter what you say, danmaku IS related to someone's mystic powers, Mokou throws fireballs, and Utsuho mini-stars!). Well, suppose it's harmless, for whom is it a disadvantage really? Rumia, with the power to make it dark? Lily White, with the power to announce spring? Flandre will still blow you up in one hit, and Remilia can manipulate fate with all the implications of it, and Sakuya can freeze time and beat you up, and Mokou is immortal, and Yuyuko can kill you with a thought, etc. Hell, even Cirno Baka has the power of "manipulation of cold". She chills you all the way up to absolute zero, you die, end of story. Basically, there's rather "a handful of useless superpowers" and "a lot of really powerful ones", not the other way around. You do have a point by saying, I quote, "It is fortunate that so far all the big nasties have consented to fight using the harmless-but-flashy danmaku style, because otherwise all sorts of planetary holocausts could've gone down by now". In fact Danmaku really has the objective to give mortals like Reimu and Marisa the ability to fight badasses like Flandre and Yuyuko without getting killed on the spot. But this is not a WMG anymore. It's frigging canon. It's in Perfect Memento.
As far as canon goes, we can be sure that danmaku can hurt and the pain degree varies. In her Grimoire, Marisa talks about spellcards such as 'Spear the Gungnir' that it feels like getting stabbed, or 'Red the Nightless Castle', which 'hurts as much as getting hit by danmaku.'
Danmaku is almost certainly related to magical power in so far as some amount of the later is required to do it, but beyond a certain level it's probably more a matter of skill then power. Reimu and Marisa are quite likely so good at it because they you know do it all the time. Touhou characters do tend to have there powers exaggerated sometimes to the point of lunacy in fanon though, for all the talk of Yukari's supposed neigh omnipotence for instances she's never actually demonstrated many special talents besides creating a large magical barrier (WITH HELP) and teleporting. Certainly she's never shown the kind of casual reality warping omnipotence that the most outlandish and vague interpretation of the curt description of her powers could be stretched to include.
Don't forget that Reimu took down many powerful humans/youkais/whatevers (Marisa, Mima, Yuka, Shinki...) before the spellcard rule creation. Not only every not so powerful youkais but even stronger HAD to accept Reimu's rule to escape a pure and merciless annihilation. Reimu was just too lazy to hunt all youkais at once, so she made a rule to prevent an uncontrolled threat. Also before mentioning any flawless hax (boundaries, fate, death manipulation), think about Reimu being THE shrine maiden and how a godly power may protect her. I guess youkais had to think about pure skill/power to accept the rule.
Still, why was Utsuho obeying the rules? She can't destroy Gensokyo when she abides to the rules and she wouldn't fear that Gensokyo vanishes without Reimu, because that's what she wanted. Heck, why would anyone cause a ruckus then? Due to the spellcard rules (and to your theory, without them) not a single youkai could defeat Reimu.
Give how smart she is, no matter how powerful, she wouldn't think about disobeying the spellcard rules just to achieve victory. Her only thought was probably just shooting around mini-suns like a maniac and hoping nothing was left.
Rating a Touhou character's power according to his/her stage is stupid.
This is made up from one thing: Sariel is the Final Boss of The Highly Responsive to Prayers, a Stage 20 Boss. If the power scaling goes up as expected (With EX-Bosses equaling Stage7 and Yukari equaling Stage8), she could singlehandedly destroy Gensokyo, the World and Chuck Norris.
We also shouldn't forget Yuuka Kazami in Lotus Land Story, now should we. She was the boss for both Stage 5 and Stage 6!
Sariel is really a stage 4 boss. Stages in HRtP are divided into 4 levels, then a boss. I think.
Nope: There are four stages without a boss, and a boss stage after each of those sets. And because of the split route, there are six characters that would build the top tier: YuugenMagan, Mima, Kikuri, Elis, Sariel and Konngara. Also, I'd rather rate the character's power by their win ratio, as it would imply Yukari would be at zero percent, as battles done in teams are not legit for the ladder (bad luck for you, IN pairs). Reimu's and Marisa's wins in SA still count, as they only take a skill of the youkai with them, making those not participate in battles.
Actually, stages in Touhou 1 are much shorter than in the shoot em ups, so a "block" of five stages would probably be a closer increase in power level to a stage in the later games, and maybe not even that.
However, with a few exceptions (read on), rating an individual's level of power based on their stage is useful when ranking them against characters in that same game. EoSD is perhaps the best example of this, starting at "non even worth considering" threat youkai, continuing to more powerful beings then ending with the "OHSHI-" level power of Flandre. This method isn't completely reliable though, as among other things it implies Koishi is more powerful than Utsuho and Ran is more powerful than Yuyuko (the latter is possible, just very unlikely).
In SA the stage 4 boss is stronger than the following two. Also in Mystic Square, you can assume Sara to be one of the strongest in Makai (even though being a stage 1 boss). Because seriously, it wouldn't make sense to fight the gatekeeper last just because she is stronger than he others.
Just because Satori is the leader doesn't mean she's the most powerful. It's not uncommon for The Smart Guy to take charge of stronger but less capable subordinates. Especially when one of those subordinates is as famously dumb as Okuu.
Koishi may not be more powerful than Utsuho (though she is very powerful), but she's definitely far more skilled than the birdbrain.
Being a final boss certainly requires a great deal of power of some kind (there's a difference between raw magical force, skill and subtlety, and broken Reality Warper-tier abilities, so most arguments regarding cases like Satori and Utsuho are based on misunderstandings and terminological inconsistencies), and not every powerful character was a late-game boss. It depends on their motivation and role in the story - Yuyuko was a stage 1 boss in Ten Desires, Hina might as well be monstrously powerful, and Keine, Chen and Yuugi were already mentioned in the Yuugi WMG below. Regarding THRtP and the Phantasmagoria games, it's probably better to consider their relative position in the game instead of their absolute stage number.
Gensokyo actually has a matriarchal society.
There are only four known males in the land, with the rest being insignificant characters who apparently spend all their time at home. Of the male characters, two are servants for female characters. one has mysteriously vanished without a trace, and one runs a shop that, despite a prime location, is inexplicably devoid of customers except a few "nuisances." Obviously, the males Stay in the Kitchen because that's what society expects of them — similarly for the men (well, turtle and cloud) who are servants to female characters. Rinnosuke decided to defy convention and try to open his own business, and has been ostracized for it... except for a few girls who are just too weird to care. As for Youki... perhaps he decided to remove himself from a society that didn't value him. Perhaps something more sinister happened. Perhaps it's entirely unrelated. Whatever the reason, he's gone now.
It's likely that something in Gensokyo's gene pool or magic field causes only women to gain magical powers, and therefore the men simply don't participate in the conflicts (i.e in the games) because they can't, due to magical ineptitude. They exist, they're just so unsignificant we don't see them. The exceptions being a FEW animal youkai, such as Genjii, and some elementals, like Unzan. Rinnosuke is one of the men who would normally not be seen in the games due to absense of powers and therefore of importance. He gets introduced in a book and from what I know, never does any fighting whatsoever.
I might as well post my theory on the subject: Most of the major (humanoid) youkai in Gensokyo are shapeshifters, who take Moe Moe girl forms to distract youkai hunters. This in turn leads to the humans assigning youkai hunting to the religious and to women, who are less easily swayed by feminine wiles. Thus, most of the characters we encounter (youkai hunters and youkai) are female, with menfolk in minor roles and behind the scenes.
If most hunters are female, shapeshifting into a moe girl holds no advantage while a cute boy might have advantages.
Genji remains male because he's a longtime ally of the Hakurei family and won't get hunted.
Rinnosuke is accepted by humans in his natural state and might not be able to shapeshift due to being only half youkai.
Unzan is too modest to shapeshift into a girl, hence his reliance on Ichirin.
Doesn't explain fairies, magicians, lunarians, gods, and other non-youkai also being entirely female. Or all of characters that are too powerful to be threatened by humans.
Humans can extend their lives by becoming youkai.
Perfect Memento states that a human who learns Shashoku magic, they become magicians. In Touhou, magicians are a subclass of youkai and enjoy the relatively longer lifespans other youkai do. If Marisa ever wanted to, she could learn this spell and extend her life.
Reimu, on the other hand, would have to perfect her border-related powers (maybe with some help from a symphathetic Yukari) and become a sukima or her divine powers and use it to extend her life or become a celestial.
Keep in mind, the magic words are "if they wanted to." Word of God states it's very easy for a Magician of some skill to "stop eating food" and become immortal. That Marisa hasn't implies it's a personal choice. Reimu's reaction to Byakuren also implies she'd possibly be opposed to the idea. Of course, if time keeps passing and the characters stay the same age, it may no longer be an issue.
Sanae may also be able to use her divinity to extend her life or become a goddess.
Given Suwako's dialogue with her in 12.3, she may well be a demigoddess already, and may almost ready to fully ascend.
Meiling's mastery of Chi could have made her a youkai. However, since this method relies on a person's spirit only, her abilities with danmaku, or magic in general, would be lower than the average youkai.
By this of course, I mean that the more useful a power is by nature, the less potential it has. Consider Yuyuko's ability to inflict death. That's all it does. However, look at some of the more 'useless abilities.'
Reimu has the ability to float around in the sky. The results? Fantasy Heaven, where she floats out of existense and shoots at you.
This ultimately means that Reimu hasn't demonstrated her true ultimate power; the ability to eat sweets and not get fat, which if applied to combat would defeat entire pantheons of gods.
the above is already used in the form of Reimu having the smallest hitbox of the games she's in.
Yuuka has manipulation of flowers. This Troper once saw an eight panel comic showing Yuuka beating up Tenshi. When she found that her body couldn't be destroyed from the outside, she ripped of Tenshi's peach, took a bite, french kissed the seed inside her mouth... I think you see where I am going with this.
Through sheer focus, Youmu can slash at ridiculous speeds, create a body double, and is in decent spots on tier lists.
Of course, these only apply to the idea that the character has honed their power to the right degree. Yukari is still the strongest Youkai in Gensokyo, because she has totally mastered her power. Utsuho may have the most destructive power, but she doesn't really know how to use it, other then Beam Spam.
Point of contention: Yuyuko's ability is actually "manipulation of death", which while mainly manifesting as inflicting death also allows her absolute control over the dead. She just doesn't, because she's super nice.
Anyone in Gensokyo or neighboring realities like Makai must follow them when engaging in combat with someone. It doesn't even cross their minds not to. Even if they've never heard of Spellcards, they will be RetConed in.
The Gensokyo Barrier has sealed the Dreams from the Earth Alternate Universe it is connected to.
A "world where children don't smile" and tender fruits are extinct; this is why Maribel's and Renko's world is a little colder and grayer than ours. Such feelings aren't completely gone, but they are harder to get to.
There are two strongest non-god beings in the Windows continuity of Gensokyo: Koishi Komeiji, the extra boss of Subterranean Animism, and Fujiwara no Mokou, the extra boss of Imperishable Night.
Although it has been said that Suika, Yukari, Yuka or even Cirno are the strongest in Gensokyo and it has been heavily implied that it could be one of the heroines (Reimu and Marisa, namely, but also Sanae and Sakuya), this, in fact, is false. Canonically, the extra bosses of Subterranean Animism and Imperishable Night are stronger than all of them. And here's why.
(Just a note here: I'm taking the fact that every boss's power goes up by the same amount each stage; that is to say, Youmu is to Yuyuko what Shou is to Byakuren.)
Let's start with Embodiment of the Scarlet Devil. Since Reimu and Marisa defeat everyone in that continuity, that places the two of them at the top of the metaphorical food chain in Gensokyo. Next is Perfect Cherry Blossom. Since Sakuya was a stage 5 boss in Embodiment of the Scarlet Devil and she defeats everyone—even Yukari!—in that game, that must mean that youkai like Yuyuko or Yukari are weaker than Sakuya and, therefore, weaker than Remilia Scarlet. Since Reimu and Marisa defeated Remilia, though, the two of them are still at the top. They also go on to defeat Suika in Immaterial and Missing Power, which rules her out of the running as well.
Imperishable Night is where it gets a little weird. Since Reimu and Marisa are only stage 4 bosses in this game, that means that they are weaker than Reisen, Kaguya, Eirin and Mokou. Because every boss's power goes up by the same amount each stage, that means that Mokou is, canonically, the strongest up until this point. Since Mokou is never in any other games, though, we can't gauge her power level against other youkai.
Phantasmagoria of Flower View is also somewhat weird. Weak bosses such as Cirno and Mystia can go through the story and defeat a shikigami and a judge of the dead (as well as Reimu and Marisa, which further debunks their status as the strongest characters).
Reimu and Marisa hack their way through Mountain of Faith, which makes even goddesses Kanako and Suwako weaker than they are. The same goes for Iku and Tenshi from Scarlet Weather Rhapsody; since they're trumped by people we've ruled out like Yuyuko and Suika, they're out of the running.
(A word on the next two games, Subterranean Animism and Unidentified Fantastic Object: they are widely regarded as the hardest games in the Windows continuity of Touhou; therefore, I will rule their characters' power levels as a bit higher than the rest of 'em.)
Reimu and Marisa—stage 4 bosses from Imperishable Night—go to defeat every youkai underground, as well as Sanae Kochiya and Koishi Komeiji. Now, although Koishi is defeated by these stage 4 bosses, Sanae, Koishi's stage's midboss, goes on to beat the living shit out of UFO's bosses which, as stated above, is probably one of if not the hardest Windows Touhou games. Koishi, then, is stronger than even Nue, which makes her approximately around Mokou's power level, and high above youkai like Yukari or Suika.
Granted, I know that anyone can win spell-card battles (trust me, attempting to 1cc UFO lunatic will teach that to you...), but Koishi and Mokou are just the two that are the "favorites to win", shall we say.
You're only talking about who has the smartest and most beautiful spellcards. 'sides, Reimu and Marisa were Extra Stage bosses more than once. And the PC98 era didn't have spellcards yet.
Additionally, Mokou isn't really all that strong (probably equatable to Kaguya considering their similar abilities). In fact, she can be killed pretty easily, which would be great if you only had to kill her once. Her only strength is that she keeps coming back again and again. A nice in-game touch is that she has multiple, disconnected health bars; each time you kill her, she "resurrects" and moves onto the next health bar. If immortality is strength, Cirno is actually in the same boat, considering fairies, canonically, can't be permanently killed either (why Cirno doesn't have a number of lives in her game, she just has a motivation meter).
On the other hand, Mokou is the only character in canon to be an extra boss for Reimu, Yukari, and Ran at the same time. That's an extra boss, a main character, and the phantasm boss all at once. Anyone that can extra for all three of them simultaneously has to have a pretty high power level.
Mokou gets killed repeatedly because the player characters know she's immortal and thus don't have to hold back like spellcard rules normally require. They would've treated Eirin and Kaguya the same way had they known going into the fights that they were immortal too.
You also have to remember, Yukari would only put in enough effort to win if it was part of her plan. If not, she'd just put up enough of a fight that no one would get suspicious.
Gensokyo is the name of a mental hospital
...and all the fantasy elements and adventures are the collective result of a bunch of fractured minds coping together. Each character's individual quirks actually come from their neuroses:
Reimu and Marisa suffer from intense hallucinations, which is why most of the world seems to be built around them. They're also paranoid, leading to them picking fights whenever they think anything strange happens.
Also, the two of them, along with Yuuka, were the very first patients of the hospital. Because they didn't have much company, they started to make some imaginary "friends" that they could fight with (well, there was Yuuka, but the caretakers thought it was better not to let them in contact with her. Not that they succeded, of course), along with recurring character Mima who Marisa claimed was her teacher and that Reimu could never defeat her (thus their rivalry). Eventually, more patients ended up in the hospital, thus there was no need for any imaginary friends when the girls finally had someone to interact with(thus explaining why the PC-98-era is Retgone).
Marisa's father abused both her and her mother, Mima. His beatings led to Marisa's severe paranoia of most males, which is why there are next to no males in Gensokyo, (other than Rinnosuke, a friend who visits her). Mima, unfortunately, was killed when she managed to get Marisa out of the house and to the hospital. For a long time Marisa was not informed that Mima was dead, and continued to believe she was around for her. Her "visits" were some of the aforementioned hallucinations. After a while they broke the news to her, and she was devastated. Reimu managed to move on, however. Marisa still occasionally hears her voice or sees her in the distance, though. This led to her belief that Mima was a "ghost" and one of her "caretakers". She still follows hints of "advice" Mima gives her, considering her as a brave rulebreaker who would let her daughter do things like beat up other patients and steal for the greater good.
Yuka was a schizophrenic gardener who made friends with the flowers in her garden, believing they could talk to her. She was sent away to Gensokyo for brutalizing an unfortunate soul who accidentally ruined her garden, killing several of her imaginary friends.
Rumia had always been a troubled child, but her insanity finally reached a climax when one night, she crept out of bed and assassinated both her parents. She has been found eating their bodies, calling herself a "youkai".
It was January and -35 degrees Celsius outside when little Cirno's abusive drunkard of a father kicked his simpleton of a daughter out of the house with nothing but a dress to protect her from the biting cold. Cirno wandered around, slowly freezing to death. By the time someone helped her, it was too late. The cold had irreversibly affected her nervous system, turning an already simple child into a mental retard, as well as completely inuring her from any sensations in her members. This lack of pain and feelings has led Cirno to believe she has gained immunity to, and subsequently control over frost, of which she is extremely proud.
Daiyousei is a quiet, homeless, but (relatively) mentally well girl who alerted child welfare when she found Cirno. She quietly comes and goes, seeming to appear and disappear like a fairy to most of the the inmates. The nurses allow these visits since Cirno is always happy to see her.
Shinki was apparently a woman who was traumatized by witnessing or being part of some occult ritual, or she herself conducted it.
Hong Meiling is narcoleptic and a recovering drug addict (see: giant catfish), at a specialist hospital because the latter restricts treatment for the former. She comes across as a doormat in the fantasies of others because she's lucid enough to know that playing along is best for everyone.
Sakuya is the one who initially insisted she be institutionalized for her drug problems. Meiling jokingly says she thinks she can manipulate time and throw knives because she always seems to teleport around and start poking her mid-conversation, though she realizes she just fell asleep.
Alternatively, Sakuya was a batshit crazy knife nut serial killer, so skilled she never left any traces after her murders, always getting away, almost as if she could stop time. She would have gotten the death penalty (or lifetime prison), but the attorney pleaded insanity.
And with that alternatively, Meiling was Sakuya's partner in crime and got the pair caught when she fell asleep while on lookout. Despite the risk, they pair are allowed to stay together since they keep each other controllably calm, though they are kept a few rooms from everyone else, not least because Meiling is a masochist to Sakuya's sadist.
Remilia comes from a family of nobles, but their fortune was lost. In desperation, Remilia went insane, becoming a serial killer suffering from a vampire complex, hiding in her decrepit mansion during the day. She would kidnap and kill people to drink their blood until she was finally stopped. She became good friends with Sakuya, who respects her as being the more hardcore of the two. Her sister Flandre (something with the genes of this family is just wrong, maybe it's all the cosanguine marriages between nobles) suffers from psychosis, and gets violently destructive when she suffers a psychotic break. She lives in a more secure ward downstairs from the others for everyone's safety, where Remilia regularly visits her.
Alternatively, the two are not actually related. Both suffer from abandonment issues and have formed some sort of familial bond as a defense mechanism.
Yukari is an old woman who suffered a stroke that severely damaged her spatial perception - she thinks she can manipulate the borders between places because she constantly misjudges where things are. Ran and Chen are her daughter and granddaughter.
Youmu constantly has out-of-body experiences, leading to a delusion that she has another, "ghost" half. This is a genetic condition, as evidenced by the history of her grandfather Youki, who was similarly delusional, but was cured. He now runs a fencing dojo. Youmu used to be one of his students, but left after her condition became too disruptive.
Yuyuko suffers from a neurological condition that makes her think she's always starving. She has to be chained to a chair or she'd bother everyone in a hysterical search for food, or if she could find enough, eat herself to death. There's a cherry blossom tree outside her window, and Youmu is her wardmate.
Yoshika may suffer from the same condition Yuyuko has except she is bound to the wall of a room, completely unable to move her arms and legs lest she attempt to eat them, too.
Nitori has an acute case of Asperger's and an intense fascination with machinery. She's in Gensokyo to treat her debilitating social awkwardness, and has just started to come out of her shell, with some thanks to Marisa.
Kanako suffers from a severe God complex, or more precisely a Wind God complex. Suwako has an extremely weird combination, she has a God complex, and she also thinks she is a frog, hopping around like one.
Sanae is Kanako's daughter, and visits her mother often. She plays along with the patients' escapades, and, as of late, is becoming more eager to play make-believe, especially now that she's compared it to her comparatively dull reality. Her humans-first attitude is a reflection of her annoyance with many of the other patients.
Utsuho Reiuji worked at a nuclear central until a catastrophic nuclear accident happened and she was exposed to massive amounts of radiation, deforming her foot, forcing the amputation of one of her arms and its replacement by a prosthetic arm, and twisting her brain. Utsuho believes that she has gained superpowers (oh, and that she's a bird). She likes to wrap herself in a sanitary blanket like a cape, and make up ludicrous plans to burn the asylum to the ground.
Alternatively, Satori is a patient with a form of autism from so far into the deep end of the spectrum that she finds normal social interaction impossible. Instead, she keeps pets, a cat (Orin) and a raven that comes past every day because she feeds it (Utsuho). Since she can think well enough to require stimulation (just being rather sideways about it), she reads the facility's medical texts; since she has a habit of diagnosing others with the same things the nurses say, they all think she can read minds.
That would make Koishi the sane one, since she would have no wierdness she would have no defining characteristic and therefore be unnoticable. The fact that no one is keeping track of her means everyone thinks that no one can, leading to her "powers". This sanity would also cause some interesting interactions with her sister... Either that, or she's just a figment of Satori's imagination.
Aya was once a world famous journalist but one day had her cover blown while following some highly illegal lines of investigation. The ensuing storm saw her reputation and publishing history made a joke practically overnight; since she lived for her job, this was enough to make her completely snap. She was admitted for her mental wellbeing, but since she's mostly harmless (running back and forth taking photos for the big story she still believes she's chasing) she's allowed more freedom to run around than the others, also making her think she's incredibly fast.
Aya's co-worker, Hatate, was so shocked by Aya's fate that she went into seclusion. She's now effectively a hikikomori, giving up high-profile journalism to write relatively boring but risk-free stories from home, and really only ever leaves to pay Aya an occasional visit. Aya, in her current state of mind, believes Hatate to be her rival; Hatate plays along for Aya's sake.
Komachi was involved in a riverboat accident that left her with brain damage that chiefly crippled her sense of balance to the point she can't even stand on her own - she needs assistance to move anywhere in a way that isn't an undignified crawl. This, combined with her train of thought now derailing at random, gives the illusion to other wardmates that she's extremely lazy. This is actually far from the truth - she still possesses the rest of her mental faculties, has an average IQ, and can communicate just fine; she just lacks mobility, leaving her very bored a lot of the time. Consequently, she has regular visits from a tutor to continue her education:
This tutor - Eiki - doesn't have any training dealing with the mentally unwell (making her seem extremely moralistic to them in contrast to the nurses) and favors a light tap on the head with a ruler when Komachi loses track of what she's supposed to be doing. "Miss Shiki" is rather strict and has very traditional values, making it difficult for her to interact with the more delusional patients.
Parsee has an inferiority complex that she expresses through emotional abuse, and often has to be isolated for the sake of the other patients' well-being; this further cripples her self-worth.
Suika, Yuugi, and ZUN are patients of a nearby alcoholism recovery center. ZUN is Aya's boyfriend, and visits her fairly often. He also somehow manages to regularly smuggle beer and sake into his room, where he has parties with the other two. In his spare time he's an author who writes fairytales based upon Aya's retellings/"news reports" about what has been going on in the Gensokyo ward lately.
Byakuren is a nurse who tries to make things better for everyone, but constant exposure to the patients causes her to fear for her own sanity.
Kaguya comes from a wealthy family, but social issues, autism, and her NEET habits eventually led the her being committed for care. Since she has such a rich family and good health care cover, she has her own private nurse, Eirin. Eirin herself should be concerned only with Kaguya's care, but her high qualifications are so useful she occasionally helps out with other patients.
Reisen is a soldier from the JSDF who suffers from PTSD stemming from a moment where she abandoned her unit during a crucial operation. In spite of her being unwell, she now acts as a sort of bodyguard to Kaguya and her entourage, scaring off offenders with a glare that seemingly drives its victims mad with fright. Tewi, on the other hand, is a shameless sociopath who exhibits anti-social behavior, and came to Gensokyo as a result of being found guilty of depraved-heart murder after a prank went horribly wrong.
'Nue' is just the nickname of a girl with Multiple Personality Disorder severe enough that, with her parents having abandoned her, nobody can figure out which (if any) of the personalities is the original. Each personality has it's own style of dress; while it doesn't fool the nurses (and in fact helps them know 'who' they're talking to), it's enough to make other patients think she's a shapeshifter.
Kyouko arrived after becoming lost in the mountains during her junior-high years. Wandering around and trying to answer the calls of search-and-rescue teams, she developed severe obsessive-compulsive behavior which compels her to repeat back loudly anything anyone says to her. Her disorder is also the reason she can regularly be found sweeping the entry of the patient ward. Her habit of greeting everyone cheerfully in the mornings is the result of a phobia of being alone (also due to her unfortunate experience).
Kogasa was abandoned at birth to an orphanage, and due to her heterochromia, was seen as a freak by all the other orphans. Due to this, she has come to believe that she literally is a monster, and developed a compulsion for scaring people in order to gain attention. She also carries around an umbrella at all times, believing it to be her only friend.
Murasa was a sailor, until one day, the ship she was captaining hit a reef and sunk. Being the sole survivor of the tragedy, she believes she's directly responsible for all of those deaths, the resulting grief eating away at her sanity until she was forced to be instilled into Gensokyo after attempting to drown herself.
Alice was a shut-in with a rampant doll obsession, to the point of preferring to do maintenance on them than take care of herself, and occasionally having delusions of them coming to life and moving around. She believes herself to be completely sane, though, and so acts rather haughty towards other patients. She is also one of the first people after the inaugural patients Reimu, Marisa, and Yuuka, explaining why she was suddenly powerful enough that the series totally reformed after she came up.
Miko was a student at a nearby university majoring in Japanese History. The stress of her studies caused her to snap suddenly one day and she came to believe that she is the resurrected Prince Shotoku. Futo and Tojiko are simply two friends who are willing to play along using the historical clan names of "Mononobe" and "Soga".
Tenshi is one of very few patients in the "Outpatient" class, only entering the hospital when she is forced to by one of her common mental breakdowns. During these, she becomes extremely violent and causes much destruction, often referred to as a form of "Earthquake" due to her last name. Miss Iku is one of the hospital staff who takes care of Tenshi when she is outside of the ward, so her arrival often means that Tenshi and "Earthquakes" are often expected in the near future. This is why she is associated with the Oarfish. Because Tenshi is often able to enter and exit the hospital at will, it is said she lives in "Heaven" or even specifically as "Ecstasy", which more refers to her ability to do things many other patients cannot than an actual place.
...and so on. Each new 'game' is a pecking order being established as more patients are committed.
The would explain why there can be a population of near entirely females, yet there isn't a huge population drop. This would result in more females, since they only have X chromosomes to give, their child would need to be a female. The men are few and far between because they still have a 50% chance of passing their X chromosome as well, and may well eventually die out.
The youkai population is almost entirely female, and not only are their reproductive methods unknown but even the weakest live for extensive periods of time. The human population however, of which we almost never see, is more evenly divided between females and males.
Youkai, perhaps even Gensoukyou as a whole, operates under a feudal system.
Weaker beings offer their loyalty and service towards a more powerful individual in return for their protection and use of their residence. Sometimes (in the case of the Konpakus) even entire families devote themselves and their descendents to an individual. This is why so many petulant, self-obsessed control freaks manage to acquire devoted followers, as for youkai (and some humans, if Sakuya is any indication) nothing is more important than power.
This is also what makes Satori and Byakuren so unusual, the servants of the latter retaining their loyalty even without her protection and the former commanding the loyalty of beings more powerful than her simply because of her kindness.
It's kind of mentioned repeatedly that most youkai are independent. And the tengu have a caste system, which isn't quite the same. Oh, and the Konpaku are humans, more or less.
Mima, meanwhile, thinks that her creation contains some potential after all and offers to train her, but after the ghost is on the receiving end of one too many beatings from Reimu Marisa decides she is too good for her and returns to her solitary training mixed with bouts of kleptomania, leading to the witch we know.
This also explains why enemies "explode" in Double Spoiler and Shoot The Bullet: once Aya's got the photos she needs, she's "won", so the magic surrounding a danmaku duel forcibly ejects the "loser" from the area.
The players are the only ones that see cute girls.
To everyone else, the various youkai look like, well, youkai. Reimu/Marisa/Sanae are excluded from society because they don't mind the appearances of the youkai, either because they are insane (Marisa), are used to it (Reimu) or are just going along with everything because they were placed on the top of the youkai mountain (Sanae).
So the player is actually Akyuu? Because she has drawings of the characters the way we see them, and describes a number of them as looking human
Alternately, the player characters see through the "cute girl" disguises of the youkai— Reimu instantly recognizes Yamame as an "enemy arthropod" and asks Suika about her— but the players themselves, being ordinary nonmagical humans, do not.
Various theories on characters.
Reimu lives alone at the Hakurei Shrine, but she's not the only Hakurei alive. The rest of the Hakurei bloodline lives outside Gensokyo, and send their eldest daughter to manage the shrine in Gensokyo every generation as a means of safeguarding the bloodline. If the Shrine Maiden gets killed before she can have a family, they can just send in another Hakurei of the same generation to resume the duties. This way there is no actual threat of losing the entire Hakurei family to rogue youkai.
Marisa is more than just a pupil of Mima, she's her next incarnation. Mima taught Marisa to use magic in order to save herself some time in her return, and her disappearance from the series means that she's taken residence within Marisa. This is even hinted towards by her old theme, Vessel of Stars ~ Casket of Star. She's to serve as the vessel for Mima's return. A 'casket' for a dead 'star', as she was an important character for the first 5 or so games. With Marisa now donning a star and white bow on her hat in Fairy War, very similar to how Mima's hat appeared, it seems that she's dropping hints towards this.
Rumia and Alice are two halves of a whole story. The Alice that we know of the Windows series is, indeed, a human that became a youkai magician, but her name isn't originally Alice. Rumia is the original Alice. The Windows version took advantage of the aftermath of the chaos in Makai and subsequently PC-98 Alice's return with the Grimoire to steal the book from the defeated young demon girl and steal her identity, sealing her memories and most of her power with a magic amulet. Being the daughter of the old ruler of Pandemonium, naturally Rumia would have power over darkness. That's all that she can manage however. The new Alice has largely used her stolen power to benefit herself, granting herself youkai immortality, and using the magical control she has over dolls to earn money from performances in the village.
Sakuya used to be a circus performer, who used that public role to assist her on her double identity as a legendary thief. Her skill with throwing knives comes from part of her act, which she practiced often to find even more unbelievable tricks she could pull off with the use of her innate ability to stop time, to keep people focused on her act. She would use their intense focus against them while she stole their possessions while time stopped, and then resumed to finish the trick. Her servitude to Remilia began when she marked her during a performance, but the vampire noticed her theft and had Sakuya arrested. Rather than have her face whatever punishment she would have normally, she took Sakuya as a servant, a role that she has since come to prefer over her old life.
Yukari isn't actually a youkai, she's really asleep all the time. Her power over boundaries allows her to fudge the Border of Dream and Reality in order to act in the real world. She does this to protect her real body, in case anyone should manage to circumvent her power and defeat her, they can't force her to do anything. Her flightyness and odd behaviour comes from the fact that she's essentially living with the consideration of dream logic as the real thing, and her odd attacks in the fighting games stems from dream logic as well. With her real body in Mayohiga where no one can find it on purpose, and two shikigami protecting it, she can safely putz around all she wants without true fear of retribution.
Keine is actually a friend of Mokou's from her life prior to the Hourai Elixir. Kamishirasawa is only her surname for the present time as part of her plan to extend her own life to be with her friend. She uses her power to rewrite history to shift her birthdate up one year, writing herself as the child of whatever women of age she knows and retroactively integrates into their family through this. She bumps up her birth year as long as feasible, then changes to another woman as soon as possible. She uses her role as a teacher to find prospective future 'mothers' for herself, as it allows her to get close enough to observe prospective girls lives before she makes a choice, condition them to her liking, or even outright propose they become part of her plan.
Reisen is an ex-member of some kind of Lunarian Special Forces team, which her powers made her a prime candidate for. Her usage of explosive bullet like shots is part of her skillset, and it works alongside her natural abilities. She would be perfect for infiltration, sabotage and even assassination, as anyone that saw her could likely be convinced it was an illusion, or otherwise driven insane by her manipulation. Reisen took an issue with this life at some point, and ran away.
This one is canon, more or less
There is a master manipulator behind every game since Phantasmagoria of Flower View.
All the events of the games, starting with Mountain of Faith, have been canonically connected. Kanako provided Utsuho with the Yatagarasu, triggering Subterranean Animism. Orin's panicked geyser blast also freed the Palanquin ship, triggering Undefined Fantastic Object. The unsealing of Hokkai is no doubt the source of the spirits in Ten Desires.
Wall of text time.
This Troper thus theorises that there is a manipulator, seperate from and possibly undetected by Yukari, that has guided the whole thing. He gave Kanako the means to move the Moreya Shrine into Gensokyo, thus providing a cover for his own entrance into the same. By taking advantage of her love for science and industry, he not only provided her with the Yatagarasu, but he told her where and how to deliver it. Since he helped her before, she would be quite willing to repay him in this way. Now an easily-manipulated Hell Raven has immense power, enough to free the Palanquin ship. Her antics do the job... partly. He then convinces Orin that informing her master of Okuu's insanity is a bad idea, and has her blow open a geyser to attract outside help. This frees the Palanquin and its crew, which are the ones he needed all along. He may well have been in communication with them, and may have enabled their ship for flight. He had long ago obtained the Jeweled Pagoda, and planted it at Kourindou where Nazrin would find it. All this together, he now had the means to get into his ultimate destination, Makai.
But! Things began to break down at the last minute. While he anticipated, indeed planned, the release of the Palanquin, he did not anticipate Nue's release. He had always accounted for Reimu and Marisa in his operations, but with Nue and her seeds of non-identification in play, the heroines felt more pressured than ever, and thus fought harder. They very nearly derailed his plans, forcing him to improvise. He intercepted Nue, and enlisted her help. Possibly via force. Nue then distracts the heroines via the Extra stage, while he slips into Hokkai. In now-unsealed Makai, he can enlist the help of old PC-98 bosses for whatever devious plans he may have. The spirits in Ten Desires? A side-affect of Hokkai's unsealing that may cause him even more touble down the line.
Convoluted, yes, but after Silent Sinner in Blue, and Yukari's brilliant masterplay, I have no doubt that this is not only a logical possibility, but a workable one. If this, or anything like it, is accurate, then we have the perfect setup for a beautiful endgame storyline in a later game.
And now, with the Touhou 13 demo out, this theory has additional support, if anything else. Simply, Yuyuko has started to suspect our hidden chessmaster (Told by Yukari over a dish of sake?), and has decided to send our heroines to either a)Determine his plans, or b)Stop them entirely. As such, she taught the heroines how to fight from beyond death (namely, the Trance mechanic from 13, a player version of Yuyuko's Ressurection Butterfly from 7), and directed them to a likely location. This explains both why she was the first boss, and explains her seemingly random hint to the graveyard. Fast forward to Stage 3. Our opponent, Miyako Yoshika, is a Jiang-shi, a Chinese vampire/zombie. She was revived and is controlled by the seal on her head. Now, the nature of Gensokyo's creation would leave absolutely no Chinese within when the barrier went up. The only known Chinese, Hong Meiling, is an import. Thus, noone should know how to create Jiang-shi... unless our chessmaster brought the secret with him from the outside! Thus, Yoshika and her fellow zombies are either his creations, or the creations of a subordinate. He's making his move.
Don't you mean "she"? There's no reason for said manipulator to not be a woman...
True, but given that ZUN wanted the final boss of 12 to be Byrauken's older brother (at first), there is a chance at the manipulator being male. And besides, proper English grammar requires that in the case of unknown gender, the masculine pronoun is to be used.
The fact that ZUN changed it shows that he doesn't want to use a male even if they're a historical figure. And most people use the singular 'they' in the case of unknown gender
Add-on guess: The destructive god behind the giant catfish in Meiling's dream-campaign in Hisentouku may be responsible for the zombies and/or may be the manipulator himself. Meiling somehow knows the secret for Jiang-shi, and she was fighting the catfish-avatar in her dream to attempt to avoid being killed, possessed, or stuff. The catfish managed to find and copy the secrets for what is necessary before being forcibly ejected by Meiling.
The "human" characters become more powerful during every interval between games.
In Mystic Square, Alice is a stage 3 boss, but powers herself up to become an EX boss. Two games later, she's dropped down to being a stage 3 boss again.
In Perfect Cherry Blossom, Yuyuko is a stage 6 boss. Imperishable Night, Phantasmagoria of Flower View, Mountain of Faith, Subterranean Animism, and Undefined Fantastic Object happen, and when Yuyuko shows up as a boss again in Ten Desires, she's fallen all the way down to being a stage one boss.
More than likely, Youmu has it right; Yuyuko only fights in Ten Desires because she's bored and has somewhat useful information. She has no reason to stop the heroines (except maybe Youmu if she suspects the incident to not be worth being gardener-less for a day or so), and she did the exact same thing to Youmu in Scarlet Weather Rhapsody (also in Stage 1). If she isn't fighting because she's bored, then I'd have to imagine she's doing it because she realizes that danmaku must be exchanged before information can be.
Reimu and Marisa are consistently both stage 4 bosses to each other. When Aya fights them in Mountain of Faith, she's a stage 4 boss to them, too, which would presumably put them all on about the same level. When Aya encounters them again in Double Spoiler, they're suddenly EX bosses.
Similarly, in Embodiment of Scarlet Devil, Cirno is a stage 2 boss. In the very next game she's a mere stage 1 mid-boss. By the time of Fairy Wars she's fallen so far behind that Marisa is an EX boss from her point of view.
Kogasa is the exception that proves the rule, in a slightly more literal sense than usual. Stage 2 boss in Undefined Fantastic Object. She's now stage 3 in Ten Desires, now as the mid-boss. Aren't you surprised?
Clearly, Reimu and Marisa are steadily getting more powerful every game. Youmu can presumably be assumed to be doing the same, since she also experiences stage 1 Yuyuko in Ten Desires. Sakuya is most likely similar as well. Sanae's harder to pin down, given that she raced on ahead and became an EX mid-boss in Subterranean Animism, but that's just because she knows better than to worry about common sense.
Actually, Kogasa is the Stage 3 midboss, so she is actually stronger, Yuyuko wasn't even trying to stop them and probably was just bored so she was weak on purpose. Alice needs to use her grimoire to be strong and she didn't use it in her PCB battle. But that doesn't mean that Marisa and Reimu aren't getting stronger, I believe you're right, but your logic is a bit wrong.
...Kogasa's appearance is so surprising that she made me lose count?
Koishi, Flandre and Mokou represent three ways emotionally troubled people react to stress and grief.
Flandre Scarlet pretty much deals with things in such an agressive way, like people would go for violence and anger to try to solve said problems.
Fujiwara no Mokou is the victim of all this, some people blame everything and everybody and make themselves the victim even if the trouble they're struggle upon was caused by them in first place.
Koishi Komeiji evades trouble and laughts at it, just like some troubled people that are in a profound denial and while they're through serious grief in the inside on the outside they want to look carefree and that they're happy all time and on their happy denial even being troublesome to others; all this in order to hide their grief rather than deal with it until find a solution.
Yukari, Sakuya, and Yuuka (and possibly other uber-powerful characters) have lived several times their lifespan.
As we know from what Komachi said in SWR, Tenshi has lived several times her normal lifespan. Now, Yukari and Yuuka are stated to be some of Gensokyo's oldest yokai. They're also some of it's most powerful yokai. It's perfectly possible that yokai aren't immortal, just extraordinarily long lived. Yukari and Yuuka, like Tenshi, just fight off the Shinigami every time they come for her, and it may even be possible that Shikieiki has stopped sending shinigami after them because she knows they'll lose. This also might tie in to in Po FV, when Shikieiki told Yuuka she was 'a little too old': Shikieiki knew Yuuka was waaaaaay past her lifespan, but since her role was not to gather souls, she merely lectured Yuuka. For Sakuya, I believe it was stated somewhere that she's lived longer than most humans do. Rather than being ghouled like some WMG say, it's plausible that she's stronger than most Shinigami are. As for why Komachi only called out Tenshi? Only Tenshi was being all high and mighty about it, and it hit a pet peeve of Komachi's. She can tolerate people like Sakuya and Yuuka because they at least don't brag about it, it's not her job to deal with in since she's a ferrywoman shinigami anyways, and doing so would, plain and simple, just be more work.
"...than a man using a pink shirt". Sure, it's not a shirt, but you dare say Ragnar isn't manly?
Rinnosuke needs an excuse. A playful Yukari dare?
What happens to the inside of Gensokyo when the barrier goes down varies due to how the Hakurei Barrier is removed.
For example, if Yukari just dissolves the barrier slowly to avoid mass destruction, she can gently tease Gensokyo over the boundary until it lands safely. If Reimu dies horribly and there are no Hakurei left to replace her (And all auxiliary personnel like Genjii, the Hakurei Orbs, possibly Marisa, possibly Sakuya, and definitely Yukari are either dead, broke, or unwilling and/or unable to help), the barrier turns off and Gensokyo impacts Japan with the force of a giant meteor from above, with cute pretty shows for the Lunarians watching from the moon. The barrier is drained of power extremely fast? Kablooey, Gensokyo goes pop and everything within gets hit by the wrath of the universe's plot hole. The barrier slowly loses power? Gensokyo safely plops down in Japan and the Hakurei Shrine is no longer a dual-existing location.
Large portions of Gensokyo have ironically perfect counterpart characters or equipment.
Flandre's short-term kill-them-all power is paired with Laetevinn's long-term magic. Remilia's long-term fate manipulation is paired with Gungnir's perfect-aim short-term. Youmu's peerless swordfighting, highly physical, is met with spirituality because she's half-ghost. Yukari's theme Necrofantasia to Border of Life, Yuyuko's theme. They're friends. ZUN is setting up a lot of connections here. Reimu's shrine-maidening to Marisa's MASTER-SPARK-THEM-ALL! Keine to hakutaku!Keine. Satori's opened eye to Koishi's closed. Byakuren's Buddhism to the Moyira Shrine's Shinto. Et cetera.
More specifically, female Youkai become Cute Monster Girls while the male ones look like the more traditional depiction. We have seen male Youkais in Genji and Unzan, who both are non-humanoid. In the mangas, especially Forbidden Scrollery, we also see more non-humanoid ones such as En en ra and the various Tsukumogamis. The tsukumogamis are particularly jarring since we have seen a humanoid one before, Kogasa, and the ones in the manga don't. Therefore, either Kogasa is not a tsukumogami, or the ones in the manga are males and we have Bizarre Sexual Dimorphism in this case.
At least for the animal youkai, this could be explained by the fact that in most of animal species there are more females than males (humans are one of the few animal species in which the gender ratio is more-or-less equal) and even fewer of them become youkai. So this mean that, at least for animal youkai, it's more probable to find more female youkai than male ones.
Gensoukyou is a role playing game
Maribel is playing Marisa and Renko is playing Reimu. All the other playable characters are unnamed friends of theirs. Mima's player was the original GM, and her games correspond to the PC-98 games. The original GM left the group after the fifth story arc, which explains Mima's disappearance after the switch to the Windows era.
The similarities between Yukari and Maribel can also be explained as a bit of GM trolling.
What seems to be an excellent descriptor of the characters? Their theme song. Think: Very few of the characters are humans rather than youkai, and those that are humans and not partially something else are at least somewhat magical or otherwise special. Eastern wonderland is still a wonderland, and as such can operate on rules completely different from our own, such as the spellcard system. Considering how unpronounceable some names are intended to be, what's more hard to pronounce than an entire song which may or may not be describing enough of the essence to work, as emphasized by the spirit world versions, changes between games, etc. And this is without taking into account location themes, which usually do not fall under said trope, mostly being objects or collective thoughts. Woe to those who annoy the Prismriver Sisters, who could play your theme song and call you. Unless they're hovering out of view following around the protagonist playing theme music all the time.
Gensokyo won't last forever
Gensokyo was never meant to be a permanent solution to the growing lack of belief in the fantastic in the outside world. Consider that canonically, the Hakurei Barrier has only existed since 1885. Now consider how relatively small an area Gensokyo is. It's in Japan, which is itself not a particularly large country. Gensokyo is probably only a few hundred square miles large, if that. The more long-lived residents of Gensokyo are already starting to get restless from the confinement, as shown by the fairly frequent incidents that Reimu has to deal with. Yukari planned this from the beginning, and has further plans for when Gensokyo can no longer stand as it is.
The characters' hitboxes are their shirikodama.
They seem to be at around the right place, and they definitely exist within Gensokyo...
Gensokyo feeds off human beliefs and fantasies in the outside world.
No, it's not a creature of them, more in the sense of the SacredRealm, which is said to change its appearance depending on who visits: It's a beautiful paradise to one of good heart, a nightmare land of death to one of evil heart. Which would explain not only the incrediblebeauty coexisting with terrible Nightmare Fuel, but also why there's no official overall layout of things geographically, and every fan game that feels the need to lay things out does so differently.
The brief invulnerability period when bosses enter is because of stage fairies
Since fairies respawn, there's no need to hold back against them. Since some of the bosses are quite capable of dying of extreme extermination violence, there's entry invuln to keep them safe.
Flandre, Koishi and Nue are different sides of one character.
All three of them are somewhat rare, and they never appear together except in one of Aya's photo shoot games, and we all know how reliable Aya is.
Sealed characters can send forth a weaker version of themselves.
In Touhou 4, 6 and 7, one boss is sealed away at or after the end of the game and a boss resembling her but weaker appears early in the game. Kurumi resembles Gengetsu, Rumia resembles Flandre, and Letty resembles Yuyuko. And in the games, the weaker and stronger bosses never meet. These bosses could keep their main spirit sealed away and send out their body to try and stop the heroes (Kurumi), draw their attention (Rumia), or distract them (Letty).
All playable characters worked to solve each incident.
Discounting the PC-98 because that's ambiguously canon, let's lay down general rules. Reimu and Marisa are stage 4 boss level and the characters who join them are stage 5 boss level, so the former are slightly weaker (and the latter equal to) stage 5 bosses overall and all are weaker than stage 6 bosses or extra bosses alone.
In Embodiment of Scarlet Devil, Reimu and Marisa went up against a queen vampire and her servants. Your general dark lord business.
In Perfect Cherry Blossom, Sakuya (last time's stage 5 boss) joined Reimu and Marisa as they took down the spirits of the dead and their leader who had mastery over death. Not easy business, but still of this world.
In Imperishable Night, last time's stage 5 boss, Youmu, joined the previous three, and all four were backed up by a powerful last boss-level or bonus-level boss (in Marisa's case, her companion's EX status was only shown in the above mentioned ambiguous canon) to take down a stronghold of Lunarians. Now even if you don't trust Silent Sinner in Blue word for word, the Lunarians are serious business. The extra boss is a human, but does have enough power to fight said Sufficiently Advanced Aliens day and night, and so does not go down easy either. The stage 5 boss in this group was a Butt Monkey relative to the previous two stage 5 bosses.
In Phantasmagoria of Flower View, Reimu and Marisa were joined by seven stage 4/5 bosses, a couple low-level stage 2 bosses, and eventually a boss who had previously been last-boss level and two others on the same level to take down a top-level official of the Celestial Bureaucracy with powers of ultimate judgement.
In Mountain of Faith, Reimu and Marisa went out against the gods of an old shrine with about the same level of power as the Scarlet Devil and company, and a stage 5 boss (Sanae) about as strong as Sakuya.
In Subterranean Animism, Reimu and Marisa seemed not to have company, but weren't alone, instead helped by bosses ranging from stage 3 Butt Monkey level to EX level, as they fought the entire forces of the Underworld and The Starscream using nuclear fusion for misguided ends.
In Undefined Fantastic Object, Reimu and Marisa were joined by Sanae in a fight against a magical mystery religion drawing power from an ancient dark realm, about as strong as the Cherry Blossom forces.
In Ten Desires, Reimu, Marisa and Sanae were joined by Youmu again in a fight against an even stronger undead army from The Time of Myths before Gensokyo and the Cherry Blossom fortress were established, led by ancient God Emperor types.
In Double Dealing Character, Reimu, Marisa and Sakuya team back up against a chaotic team-up of creatures of all kinds, of a comparable threat level to the first ghost army or the demon world cult.
Also note that EoSD, MoF and DDC each started off a new story arc of Touhou. Over the first, the threat level started out about average but rapidly escalated, over the second it started about the same, then quickly spiked but never took off quite so much as last time, and this time the threat is already starting out unnaturally high.
The males of Gensokyo can't use spell cards because the XY chromosome prevents it.
A small, unnoticed mistake or mispronunciation when Yukari set up the barrier caused a flaw which makes all magic in Gensokyo dependent on the user having the female XX chromosome. Thus, male humans and youkai have been essentially locked out of being able to wield spell cards.