Tetsusaiga was inspired by Excalibur.Look at the facts:
When Shippou matures, he will eventually have nine tails.Who knows? He may even become as powerful as Sesshoumaru.
Tessaiga and Tenseiga are both ZanpakutoThink about it. They both have names, they both have strange powers, and they're both empathic weapons with minds of their own. In fact, Tenseiga's Meido Zangetsuha is very similar in appearance to Ichigo Kurosaki's Getsuga Tensho, which is fired from his blade, Zangetsu. Furthermore, at one point Inuyasha has to battle the Tessaiga to gain one of its abilities, which is very similar to how Ichigo had to battle Zangetsu to achieve Bankai. Lastly, Tessaiga's Wind Scar and Ichigo's Getsuga Tensho are both attacks in the form of a massive wave of energy fired from the blade.
Tessaiga will become a weapon for the Spiral Races.After all, it can now pierce the earth, go through the heavens, and cut forward into tomorrow.
Inuyasha was pregnant with Koga's pup and gave birth to Momiji Inubashiri.Seriously, think about it, during Kagome's absence of more than three years, there is plenty of time for that to occur, and extrapolating, Gensokyo is essentially a piece of the feudal era (not to mention a land of lores), it is possible that Koga and his tribe lives there now. More, Momiji's Tengu qualification seems more like a Job Title, and plus, take a look at the family resemblance.
Shippo's parents were bigots against half-demons.Shippo is treated as being quite young. However, he is shown as being rude, uppity and down right snobbish when it comes to Inuyasha. Children usually learn such behavior from their parents. Perhaps his parents taught him that, even if it doesn’t seem like it, all half-demons are naturally inferior to full-demons such as himself and deserve to be treated as the second-rate creatures they are. It might be that this bigotry was exclusively for half-demons, as Shippo seems to have no problem with humans or demons, but seems disgusted by half-demon Inuyasha. This explains his apparent hatred for Inuyasha might explain his constant need to amplify Inuyasha's flaws, constantly get him in trouble with Kagome, and insulting and making fun of him. It can all be summarized this little gem from his opening episode.
Shippo (dismissively): Don’t make me laugh! You wouldn’t be able to taken them on! You’re just a half-demon, aren’t you? I can smell the human in you! Just a half-demon, you should stay out of demon affairs!
Koga does not really love KagomeFirst, let me point out that wolves are always very affectionate with their mates. However, Koga is possessive, forceful and doesn't even seem at all concerned with Kagome's happiness. All Koga ever dose is treat Kagome like some prize to be won. Always calling her 'his woman', like she was his property, and talking to her like some sort of faceless object instead of a person. And it also seems that Koga never really loved Kagome, just her abilities and the power that they offered. He doesn't love Kagome, but he certainly loves the idea of having all the Jewel Shards from himself.
The Inu no Taisho is actually GodHe seems to know everything about the future, even preparing for the regrowth of Sesshomaru's arm, his love of humans and Inuyasha's need for the Tetsusaiga. Plus, he's really hot, I'd like to worship him.
Rin is the reincarnation of Kikyo.Although Kagome is the reincarnation of Kikyo, she's a time-traveler, and the Shikon that was in her and got broken up has traveled through time inside her. There's no reason that Kikyo can't be reincarnated in Inuyasha's time; the Shikon could still exist inside her, intact. (You'd have the Shikon existing in two places at the same time because the one from Kagome came from the future.) The idea of it being Rin specifically stems from the statement in at least one episode (Jaken Falls Ill) that she looks like Kagome.
Kikyo has not been reincarnated yet at allAgain, Kagome is her reincarnation—but Kagome has traveled through time. It's entirely possible that Kikyo died and wasn't reincarnated at all in her own time. When she was restored as an undead priestess she started out without much of a soul but eventually got her soul back—the series has been awfully inconsistent on whether Kikyo has a soul and especially later on and at her death, the idea that she is just a puppet animated by hatred and that she doesn't have a soul because it has already been reincarnated doesn't at all match what we see.
Rin is actually Kagome's mother.Either through her travels with or by Sesshomaru's abilities or contacts, Rin's aging was slowed to demon levels. This explains why Kagome's mother doesn't fret too much about her daughter going back in time to fight horrific man-eating monsters. It is because she knows what will happen/happened already. Rin just took the long way through history; changing identities, altering her looks, and adopting normal people who age (like Kagome's grandfather) to maintain her cover.
Kagome is really unconscious/in a coma/dead and the entire show is either a dream or the afterlifeWhile looking for Buuyo, her cat, she fell down the well, bumped her head, and is either experiencing a dream, a coma, or death. This troper cites the hentai doujin Alice in Sexland (which, as the name implies, takes its inspiration from Lewis Carroll's works, as does Inuyasha) as inspiration, where it is revealed that this is exactly what happens to the protagonist, specifically the "she's dead and this is the afterlife" variant.
The Sacred Well is in fact a Stargate capable of time travel and all demons are AncientsThis explains the absence of demons in the present era, as they are for the most part extinct in the modern era.
The Sacred Well is in fact a Stargate capable of time travel and all demons are Goa'ould and genetic experimentsNuraku's status as a former human seems to fit really well with being possessed by a snake - right down to the injuries that he wouldn't have otherwise survived. Sufficiently advanced cloning might account for the creepy children walking around. And doesn't Kikyo's resurrection fit really well with cloning as well? Being "A creature of bones and graveyard soil" sounds like a very poetic way of explaining that you are someone's corpse's clone. And very aware of your deceased status. And, if you assume that the story has had five hundred years or so to mutate, science theoretically could account for a lot of the other strange things in the series. Oh, and Kagome is a pre-Ascended.
Inuyasha's time is not Kagome's history, but an alternate dimension in slower time.This is why in Kagome's past, the demons and giant bugs and monsters were all considered pure mythology: because they were. They never existed in the human world, and Inuyasha's world just happens to be roughly coincidental with our time, 500 years ago. Anything that hinged on being transported from the past to the present was, because of the linkage of events in Inuyasha's world and out history, left there by what would seem to be a complete coincidence. This is why Kagome doesn't just look for a journal (in a place she hadn't been, say, in a metal box under some random tree or shrine) of where all the shards are in the present, find all the shards, and leave their locations in a journal in the exact place she'd first looked. She couldn't do that, because the information wouldn't have existed in her own past. This is also why the characters tended to shy away from time travel references, and if Kikyo's soul (and the Shikon Jewel) could be reincarnated across a dimension, this does not eliminate the possibility that Rin is one of Kikyo's reincarnations, though not necessarily the one directly succeeding Priestess Kikyo.
Kagome is her own great-great-great-etc-grandmother.Since we haven't seen any 1/4th demons we can assume any demonic traits in her family diminish over time.
Kagome is descended from every one of the cast from the feudal era who lived to reproduceBut especially Miroku, Sango, Rin, Shippo, Inuyasha, and herself.
The shard for the Mask of Flesh still exists in the past.And there will be a movie for it.
Kagome will put the shard from her time into the mask herself.And then try to hide it, so it won't be found until it's supposed to be found.
Kagome is stuck in a time loop and will never be able to rest in peace.Kagome decided to stay in the past. Which means in 500 years, she'll be born again, go back to the past and face the same adventures, stay in the past again, and in 500 years...
Kagome is really a Time Lord.
Everyone ready for this? Sesshomaru is... Santa Claus!In the final chapter, we see him flying in a gift for Rin, hmmm. Jaken and his brethren are elves and A-un is the first reindeer. The red suit? A robe of the fire-rat. What's more, Sesshomaru can fly, has white hair, an extra long lifespan, and super-speed. The Polar Express brings us the final peace of the puzzle: Santa is wielding a rather familiar looking whip...
Inuyasha eventually finds a way to rid himself of the subjugation beads and replaces them with fakesThink about it: anytime Kagome is back in her own time and the others are busy with other matters, Inuyasha could have been out making inquiries as to a means of breaking the spell and then sometime later in the series, when no one was the wiser, replaced them with fakes. Just imagine the look on Kagome's face when she suddenly realizes her "sit boy" command no longer works...
The Anime takes place in the past or AU of Fatal FrameWatch Fire on the Mystic Island and you will know...
Kikyo is a Nobody.She seems completely controlled by memories of her former life, she's basically half of Kagome, and she lacks a true body, instead subsisting on a body composed of human souls.
Naraku will be reincarnated Charlie The UnicornHow long can he be a Karma Houdini?
Tenseiga's main purpose was to create Bakusaiga inside SesshoumaruIt was given to him in lieu of Tessaiga, and is one of the two youtou we saw that was not actually forged by a smith but came from a youkai's body (the other being Abi's halberd, which came from Naraku), and unlike Naraku, Sesshoumaru doesn't have the inherent ability to shift his own body to anywhere near that degree on purpose. Combine that with the fact that we know that Tenseiga can repair itself (which Tessaiga can only do when taking back youki that was stolen from it) and that Sesshoumaru's getting Bakusaiga after giving up on his attachment to his father's momentos parallels how Tessaiga usually gains powers after Inuyasha passes a test of character rather than just defeating another youkai/weapon, and it seems likely that Inu no Taisho gave Sesshoumaru the allegedly weaker sword to teach him kindness, let him perfect the Meidou Zangetsuha for his hanyou brother who can't survive the jyaki of Hell, and incubate a truly destructive weapon to give to his eldest son when said son has proven his worth and learned to stop relying on his father's strength.
The series takes place in the Rosario + Vampire universeThe reason that there are no sentient youkai in the future is because they're willingly undergoing a masquerade to prevent from being hunted down (the non-sentient ones are either kept in captivity, hunted to extinction, or never coalesced in the first place due to the relative lack of constant warfare and death in Japan in the last century or so — with notable exceptions). It helps that their werewolves are speedsters in their universe as well (Koga's new respect for humans plus the massive decimation of his tribe by Naraku plus extinction of the Japanese Wolf equals mass crossbreeding with humans, other youkai and hanyou, forming a new breed). Inner-Moka is a long distant descendant of and genetic throwback to Inuyasha and Kagome, having the former's hair and the latter's taste in high-school uniforms and pantyshot-proof miniskirt powers. Sesshoumaru and/or a 500 year old, Nine-Tailed Shippo are members of Youkai Academy's board, and in fact were the ones who suggested Moka and Tsukune's rosaries based on Inuyasha's and Miroku's, respectively.
The series takes place in the YuYu Hakusho universe.There are demons in the past but not in Kagome's present because sometime between the two, the barrier between the two worlds was constructed. The well is a time-portal that transports the user back in time rather than to the Makai. Shippo is distantly related to Yoko Kurama. Kikyo was a distant relative of Yusuke's ancestral father, explaining her impressive powers. Since Kagome is her reincarnation, when she and Inuyasha had kids, Kagome eventually passed this relation on to Yusuke Urameshi!
The series takes place in the Harry Potter universe.The reasons the youkai are not seen in the present are roughly similar to that of why wizards aren't seen. Whenever something magic related goes wrong, such as the Noh Mask episode, there's somebody there to cover it up and/or fix it - think of it like Japan's version of the Ministry of Magic. Also, the well that connects the two eras works the same way as the Platform at Nine and Three Quarters.
The time traveling elements are the result of Executive Meddling.While Inuyasha is practically driven by Fridge Logic, most of the time it can be Hand Waved with contrived Magi Babble. The one thing that doesn't make sense at all is the whole issue with Kikyo being unable to being resurrected because her soul has already reincarnated, when it's plainly obvious that it has not *yet* done so. The only way it could make sense is if Kagome was born at some point between Kikyo's death and Inuyasha's awakening. Oddly enough this period is "about fifty years", which is just too perfect for Kikyo to be reincarnated normally. Think about it, a reincarnation could be expected to skip a generation (about thirty years) and Kagome is about sixteen years old, 30 + 16 = 46, which is pretty close. There are no other justifications in or out of the plot for this time skip. The closest thing is Miroku's back story. The cursing of his grandfather, his father's death and his growth into maturity also fit this timespan, but that could easily be reduced to under twenty years (replacing his father for his grandfather). Rather it seems as if Miroku's back story was adapted to theoretically original, feudal era Kagome. The idea is that someone suggested using a girl from the modern era to make the manga more relateable. Of course it could be that Rumiko Takahashi herself came up with the idea, but the time traveling stuff really feels bolted on after the "core plot" was done.
Kanna didn't tell Kagome how to defeat Naraku just because she didn't want to die.She did it to avenge Kagura as well. Just before Kanna receives to the order to fight Inuyasha, she's seen performing a memorial rite to her sister. Kagura also seemed to be in her thoughts while fighting though that she could have just have been thinking about death in general.
Shiori is a dhampyre.Her father and his clan resemble vampires, and her mother is a human women. She will eventually grow to possess vampire powers.
Rin IS KagomeJust to add even more Mind Screw to the series, and borrowing from some of the above theories: Rin is the reincarnation of Kikyo and that's the reason she couln't be resurrected: "Her reincarnation had been born already" as a common girl. After the end of the series, Rin will have an accident so severe her life will be in danger, and not finding the means to cure her in the past, Inuyasha and everyone else will work on a way to force the portal in the well to open. They are able to send her to the future, but earlier than what they expected, and Kagome's family will take care of her. The Trauma will make Rin to get amnesia, and the little she remembers about demons and whatnot will be threated as fantasies by her new family.
The cast are ancestors of the Ranma ½ castOnly Six Faces and Takahashi's fascination with reusing character archetypes aside, the similarity in looks and personality can support such a WMG. This means Ranma (descended from Inuyasha directly) and Akane (descended from Kagome's brother) are distant cousins, but people in Japan tend to be more closely related than elsewhere anyway because of the geographical isolation. Other ancestries:
Other demons can travel through the Bone-eater's WellKagome can only travel through the well if she has a Shikon jewel shard, but Inuyasha goes back and forth without needing a jewel. Shippo and Sota both try to go through, but fail, even though they have fragments of the jewel. This leads me to believe that the jewel isn't important to traveling through the well, but strong powers are. The jewel, combined with Kagome's own spiritual power, makes her strong enough to pass through, but when Inuyasha takes her jewel shards away, she can't travel through the well. Inuyasha, even though he's a half-demon, is the son of Inu-taisho, and is thus very strong. We see that in his fight scenes, when he's able to defeat powerful full-blooded demons. Shippo may be able to go through the well when he's older and his powers have had more time to develop, but when he tried, he was still too young. Mistress Centipede and (in the movie) Sounga were both able to travel through the well without jewel shards as well. Thus, if they tried, other powerful demons like Sesshomaru, Naraku, and Koga would be able to travel through the well easily, and humans with strong powers like Miroku could, too, if they had jewel shards.
Miroku's mother was sucked into the Wind Tunnel during childbirthing, which is why she's never mentionedNow there's also the chance that Miroku doesn't even know about this, since he would have been a baby at the time. But if she was "gone" before he even got to know her, then he'd have reason to ever really mention her or have any flashbacks of her. Yes, this is a bit grim (and a nasty way to go) but it's also makes some sense. Miroku always had that Wind Tunnel, so we can assume he was born with it. Since they would have waited until baby Miroku was birthed before they could even think to put beads on the cursed hand, there would be some moments that the Wind Tunnel was going off without anything to stop it. Considering babies are normally birthed head first, then his palms were most likely to be facing in his mother's direction. And she hardly would have been in any position to avoid being sucked in. This could also explain why once he got Sango to agree to marry him, he wanted to wait until Naraku was defeated. He cared for her too much to risk her life that way. Or, given that Miroku's personality, he probably wouldn't risk any woman's life that way just to have a child (unless there's some unmentioned backlash to letting that Wind Tunnel take the last generation of a family, such as sucking in all of Japan in that final vortex), he may only be roughly aware that the child bearer of someone cursed with the Wind Tunnel will never be around to raise their child but not know of why (maybe assuming it is part of the curse). So he just doesn't want to do something that'd cause him to lose Sango.
This whole universe is a scientific demon/human breeding experiment.Think about it. Demons are completely different species from humans. Even if a demon and a human had a child, it wouldn't result in a half-breed... Unless there was scientific meddling. Some scientists created this feudal era-esque world underground and put some oblivious citizens in it. As for the well, it's an elevator into this world. The scientists put it underground because that's where demons thrive. Among the citizens are actual scientists, making sure that no one questions this forever-feudal world.
Inuyasha's mother was killed by a powerful demonIt's never stated that she died of illness and since demons are likely after Inuyasha for being the son of the Great Dog General as well as a hannyo, one might've targeted him and she pulled a Heroic Sacrifice to save her child, leaving him to run from various demons after his life, for being a hannyo. The reason he doesn't talk about it much is because it's too painful to tell.
Inuyasha's hair isn't really hair, but a mane.While Sesshomaru's hair appears more natural, that's because he can actually transform himself into a dog demon, meaning he's completely human-looking in his "disguise." (which is why Inuyasha has dog ears and not Sesshomaru). Inuyasha however don't have the dog transformation ability, so as a "compensation" he has both dog ears and a dog demon's back mane to still give away that side of him.
Both Wind Scar and Tenseiga's healing ability were stolen from other demons and Tenseiga's healing ability isn't complete.Tessaiga was built to steal other enemies' abilities so why wouldn't Wind Scar be stolen like the others? Not to mention how Tenseiga was cast off from Tessaiga so that Sesshomaru could complete Meido Zangetsuha so that Inuyasha could claim it so why can't the Healing Ability be another incomplete technique to be claimed by Inuyasha once completed.