Accidental Innuendo: The sword Tessaiga is astonishingly phallic. It even throbs with warmth when "awakened" and grows hair on its hilt. The reason the sword was created was for a WOMAN. The sword is "awakened" by "protecting" a WOMAN. Plus powerful energies being "released" from it.
Would it be a stretch to say that Miroku is more desperate than lecherous? After all, if he doesn't have an heir before the Wind Tunnel consumes him, well...
The old lady from the Demon's head arc, is she really a fraud or is it merely Obfuscating Stupidity and she is actually more powerful than she seems, especially since she's not unnerved by the demonic aura that keeps everyone in the main group on the edge.
Arc Fatigue: Most agree that the series was much longer than it needed to be. Naraku had ridiculous Joker Immunity until the last act. The love triangle between Inuyasha, Kagome, and Kikyo dominates so much of the story and is resolved so late into the extremely long-running series that many fans were heartily sick of it, especially given how obvious it was that the outcome was a foregone conclusion. The story was also dragged out by Inuyasha's group being full of Chronic Hero Syndrome, helping anyone in spite of Inuyasha noting this draws them away from finding Naraku and thus the main plot. The Final Act reverses this issue, cramming more than 20 volumes into 26 episodes, at the sacrifice of one chapter involving a regenerating tree hermit demon never being adapted in favor of Kanna's character development.
Kikyo and Kagome, either good foils to Inuyasha or incredibly bad influences on his behavior. Kagome being extremely clingy and getting jealous for any reason, even if it's not justified and Kikyo, who constantly avoids him and/or manipulates him into getting what she wants. Both their problems (going back to the present to graduate and finishing off Naraku when she's not capable) respectively have dragged down Inuyasha on more than one occasion.
Over the The Final Act, which crammed over 20 volumes into 26 episodes. It's either considered an Even Better Sequel from the last few seasons of the anime because of the fast pacing and removal of a lot of filler, or it's considered just painful to watch because of said pacing being too fast (particularly if one is familiar with the manga), cutting Character Development, rushing a lot of the storylines and leaving many Plot Holes as a result.
There's even a small one over whether the original anime is a good adaptation of the manga or not. Detractors usually dislike the anime for adding too many pointless filler moments or even entire episodes, while removing some other important moments of the manga. A second group will complain on the characters, particularly Kagome and/or Kikyo, being portrayed as more unlikable than their manga counterparts, i.e. Kagome in the anime has a tendency to be more short-tempered and have more "airheaded" moments, while anime!Kikyo appears even more aloof and holds her grudge towards Inuyasha longer. Still, the majority of the fanbase will greatly enjoy the anime despite its flaws.
Naraku's defeat. The revelation that his true wish had been to have Kikyo's heart had fans either finding it a touching, final moment to showcase his human heart in the end, or a complete deviation from his consistent portrayal as a Complete Monster through the entire series, next to Onigumo having been stated to have only been a part of him, which made said revelation come a little out of nowhere to some fans.
The ending. Fans either find it a touching and satisfying wrap-up of the series, or quite underwhelming given the lack of any real emotional payoff between either Sango/Miroku or Inuyasha/Kagome, or between any of the main cast for that matter. While Sango and Miroku were at least given Babies Ever After during the three year time-skip, fans never quite forgave Takahashi for not giving Inuyasha and Kagome a single kiss. The Final Act would eventually fix that last one though.
Complete Monster: Naraku is a merciless half-demon who, desiring to become a full demon, will stop at nothing to obtain the Shikon Jewel, the object that can give him this power. The lengths he goes to cause nothing short of tragedy in every single one of the main cast's lives, something Naraku does not care about. As the series goes on, Naraku even resurrects a group of mercenaries with policies that made them little better than serial killers, just to keep his opponents distracted from his true goals. He happily has his minions kill innocent villagers just to lure the protagonists to him. Excelling at manipulating others, Naraku kills Kikyo, a love interest of both Inuyasha and the man his demonic body was formed from, to prove to himself that he's incapable of harboring tender feelings towards her. Not satisfied with simply showing this to himself, Naraku went a step further by destroying Inuyasha and Kikyo's relationship, leading to 50 years of mistrust between the once-loving couple. Keeping his own minions in check by the threat that they are created from his magic and he holds their hearts, which he proves good on if they disobey him, Naraku's deeds clearly prove what he hoped to learn from his actions with Kikyo, that he is utterly devoid of compassion.
Covered Up: Of the Translated Cover Version variety: Australian pop singer Sophie Monk's Come My Way was covered by Namie Amuro as "Come" and used as the 7th end theme. Try finding a video where it's not listed as "English cover".
Sesshomaru. Character Development eventually renders him more sympathetic, but even prior to that he already had a substantial fanbase willing to overlook how in his early appearances he made several attempts at murdering Inuyasha and Kagome over a sword that he honestly didn't even need. In the manga he chops someone's head off just because he was standing there in his introduction.
Koga. A lot of fans, especially shippers, are quick to forgive and forget his history of siccing his wolves on human villages for their meals, kidnapping Kagome to make her his mate and force her to gather jewel shards for him, and in general acting like other youkai in that he looks down on normal humans and especially Inuyasha for being a half-breed. Character Developmentdoes make him more heroic, but he's far from the Nice Guy many depict him as. It might be more a case of Characterization Marches On as the narrative and characters themselves seems to forget about Koga's villainous introduction, as he goes on to be an overall Anti-Hero instead.
Naraku. Unlike the above two, he has no Character Development, and he tortures, manipulates, and tries to kill every member of the main cast several times over.
Ear Worm: A good deal of the openings and endings.
Many complain that around the third or fourth season the anime begins to drag, pace-wise. This is a complaint of many of Takahashi's work - namely that they're good, but tend to go nowhere fast. However, this doesn't happen as much in the manga, since the aforementioned seasons of the anime are filler-heavy.
Oddly, the second series has the reverse problem. Well over 100 chapters are condensed into a single season of 26 episodes.
Yura of the Demon Hair was in two early episodes as a random Monster of the Week and yet she somehow amassed a decent fanbase and a ton of fanart due to her alluring design, speaking habits, and unique hair-based powers. Many of her fans had lamented over her death, feeling and believing that she could've been an interesting recurring character for the series. Some fans have even gone as far as saying that she could've made a great addition to the main cast given her unexpected popularity.
The Band of Seven, a bunch of True Companions who were basically bit players for an arc (they were just serving Big Bad Naraku, after all) but damn if they're not well received and it's one of the best-remembered arcs from the original series' run.
The Panther Deva quartet (Toran, Karan, Shuran, and Shunran), much like Yura as already mentioned above and despite being part of an anime-exclusive Filler mini story arc has also amassed a decent fanbase and a ton of fanart as well due to their character designs, their own respective Elemental Powers, and Backstory of their clan's past battle against Inuyasha and Sesshomaru's father. Unlike Yura, who was Killed Off for Real, the Panther Deva quartet had survived their battle against Inuyasha and company (although Karan, Shuran, and Shunran were temporarily killed by the Panther King only to be resurrected by Sesshomaru later on) while burying the hatchet between them and just like Yura's scenario, fans felt and believed that the Panther Deva quartet could've been interesting recurring characters who would've also made great additions to the main cast of the series as well.
Although she started out as an anime-exclusive character before eventually becoming a Canon Immigrant to the original manga, Ayame has her own small yet loyal fanbase who loves her character design, Plucky Girl personality, and hilarious interactions with Koga.
Esoteric Happy Ending: Inuyasha and Kagome are hinted to be married and are living happily with one another, however the probability that Inuyasha will age much slower than Kagome is never mentioned, meaning he'll most likely still be young looking when Kagome (and Sango and Miroku for that matter) are old. Also, it's never confirmed whether they can still use the well, meaning Kagome could possibly be separated from her family forever.
As already mentioned above, Yura of the Demon Hair was in two early episodes as a random Monster of the Week and yet she somehow gained plenty of fanboys thanks to her sexy voice and Stripperiffic outfit.
Kagura is also pretty attractive for a demoness and gets Clothing Damage to the chest, twice! Although the anime has her breasts covered up during her Clothing Damage, the manga has no problem showing her breasts completely uncovered! Cue nosebleeding fanboys.
Believe it or not, Naraku himself has plenty of fangirls, when he isn't shown with Body Horror.
Toran, Karan, and Shunran of the Panther Deva quartet before their HeelFace Turn.
In fact, any normal looking evil demons are pretty sexy themselves.
Fandom-Specific Plot: You can't swing a Tessaiga in the fanfiction community without hitting a fic where characters from the feudal era appear in the present having lived through to the modern era. Charms and spells to mask youkai as normal humans are pretty much a requirement, too.
Fanfic Fuel: Giving Inuyasha the ability to transform into a giant dog beast like Sesshomaru and their father.
In America the show's Periphery Demographic is much larger than its intended audience, and is considered the most popular girls' anime, matched only by Sailor Moon... despite being a Shōnen show.
Inuyasha is also very popular in Canada, as it and Gundam Wing helped kick off the airing of teen-oriented anime on the YTV network, not to mention that both shows feature Canadian dub casts from The Ocean Group.
This show is very popular in Vietnam as chances you would see comments from Vietnamese speakers are high in the internet, and to the point the OST is also used in Vietnamese media and films (though it probably doesn't include credit and permission however).
Growing the Beard: Once Kikyo is revived (and, more importantly, we discover that someone turned her and Inuyasha against each other), a much more complex and intricate plot arose from what had previous been fully a Monster of the Week story. While it strongly contains the previous elements, the story would focus more on the group facing a far more intimate enemy than they had previously faced. And in Final Act, the anime began extremely fast-paced and didn't give the viewer enough time to digest all of the information being thrown around. However, after a few episodes, the pacing was fixed and the series handled the grand finale episodes quite decently.
Hilarious in Hindsight: During his first appearance, Sesshomaru makes the Nothing Woman take the form of Inuyasha's mother to extract the location of their father's grave from him. When Inuyasha claims he's not fooled since his mother is long-dead, Sesshomaru convinces him that he brought her soul back from the dead and gave her a new body, and Inuyasha seems to believe that such a thing actually is within his brother's power. It totally isn't, but later in the series when he gains mastery of Tenseiga, resurrecting the dead actually does become one of his trademark abilities.
Jerkass Woobie: Kagura, Inuyasha. The former is forced by Naraku to do his whims and only can be free on death, all she wants is to be independent and free. The latter, has his mother dying at a young age, hunted down by both demons and zealot, demon hating humans from that young age, his own half brother despises him, a malicious Big Bad forces his first love to betray each other and that's not even getting into the constant abuse from his allies, justified or not. It's no wonder he's abrasive to everyone.
Kagome is Type B: Because she is the easiest character for a girl to relate to, she is paired up with tons of characters while the author projects themselves onto her.
For his part, Sesshomaru is Type A: He is the most lusted-after male character, so girls usually pair him with a female character that they can relate to (usually Kagome) and project themselves onto the female as a sort of Wish Fulfillment fantasy of putting themselves with him.
Les Yay: Episode 98. "Kikyo and Kagome: Alone in a Cave" (the title speaks for itself), focuses on the two putting aside their differences for once and working together to survive. The episode title alone sounds precisely like a fanfic prompt.
Like You Would Really Do It: To no one's surprise, our heroes were able to get the Sacred Jewel shard out of Kohaku's body without killing him.
Magnificent Bastard: Naraku, especially by the Band of Seven Arc, when he managed to get both Hakushin, a holy priest and the entire Band of Seven to serve him with a few good choices of words.
OSUWARI/SIT! In actuality, Kagome uses the control collar less and less over the series, not every time he says something off. It's also more played up in the anime than the manga, as she mostly stops using it the way she did earlier on around volume 7 or so.
Sango slapping Miroku for groping her. She stops slapping him after he proposes, which happens almost halfway through the story.
Naraku crosses it when he breaks up InuYasha and Kikyo, which leads the former to being pinned on a tree for 50 years and the latter to her death, as well as putting a curse on Miroku's family that slowly destroys them; and that's before he's even properly introduced. And once he is introduced, it's really hard to pick when he crosses in the main story, things like turning Kohaku into a Tyke Bomb to kill his own family and then uses that guilt to make him do his bidding, landing a mortal wound on Kikyo at Mt. Hakurei, having Kagura and Kanna killed because he had no more use for them, trying to have Kagome kill Inuyasha the same way Kikyo sealed Inuyasha and killing those allied with him once they served their use. It is taken even further by the anime, where he really crosses the line between The Corrupter and Evil Genius into an utter monster when it's revealed that 15 years ago he tried to kill a young priestess named Hitomiko just because of the small possibility she might pose a threat.
Taigokumaru, a nasty bat yokai who manipulates his own granddaughter to do his bidding crosses it when he reveals that he murdered his own son for fraternizing with a human.
Goshinki crosses it when he gloats to two orphaned village children about killing their parents earlier on and had planned to do the same thing to them had Inuyasha and his friends not came to save them at the very last second.
Renkotsu when he kills Jakotsu to get his Jewel Shard.
Moryomaru when he gloats about Kagura's death.
Gantenmaru and his men cross it when the former drains an innocent woman's essence in front of Inuyasha, killing her in the process and the latter cross it when they still help their boss even after he's revealed to be a blood sucking demon.
Narm: A lot of the drama of "The Final Act" is hurt by Kohaku's heavy involvement. Not plot-wise (there's a lot to wrap up there), but because his English voice actor is a master of Dull Surprise.
The dog demon forms of Sesshomaru and his and Inuyasha's father can come off as more cute than scary due to the rather feminine-looking dog ears.
While the manga is good at producing frightening demons Magatsuhi's true face can be more Narmy than actually scary.
One-Scene Wonder: Due to the long nature of the series, several characters whose prominence is in one arc and never appear again are this, including an old exorcist woman from the Demon head arc, several possible Ship Tease interests and a great deal of demons and villains whose traits are as or more so interesting than the main villain and his overall scheme; most particularly the Band of Seven.
Hojo, for his inability to catch a hint that Kagome isn't interested in him.
Kagome's friends (Yuka, Eri, and Ayumi) can also count, as their sole purpose in the story is to keep pressuring her into dating Hojo.
Ship-to-Ship Combat: The Kikyo/Inuyasha and Kagome/Inuyasha shippers hate each other, and if they were given the chance they would take up arms and start physically fighting. Then the shippers for any of those three with Koga, Sesshomaru, Rin and/or Kagura (or any of those four with one of the other three) would get pulled into it for one side or the other, and it would spiral out of a two-sided war into a multi-melee brawl. About the only shippers that wouldn't get involved are for Sango/Miroku, as the most official and least ambiguous of the series' pairings that isn't really a threat to other pairings nor do others threaten it... but there are periphery fandoms for pairings like Inuyasha/Sango and Miroku/Kagome. And let's not touch on the fandoms for Kagome with one of the Band of Seven, Koga or Inuyasha with Ayame, or any of the above with Naraku.
Some Anvils Need to Be Dropped: In-universe for Sesshomaru: 1) Compassion is a good thing. 2) You don't need your brother's sword. 3) You are NOT infallible. 4) No, really. YOU DON'T NEED YOUR BROTHER'S SWORD.
Squick: At some point, the group needs to drink a mix of blood from other dead animals that was first sucked and blended by Myoga, then spit out into bottles.
Strawman Has a Point: Inuyasha often complains about the group's many divergences to investigate something or help someone unrelated to their quest to defeat Naraku and reclaim the Jewel shards. He is universally treated as an uncaring Jerkass and overruled. However, Naraku is an Evil Overlord out to rule Japan and probably more, and feudal Japan is a Crapsack World where humans and demons alike slaughter villages on a weekly basis. Stopping Naraku and getting his massive shard of the Jewel into safer hands would do a lot of good on its own, and it's rather unreasonable for the group to stop and help every single civilian in need at the cost of delaying their journey and putting themselves in danger.
Shippo, considering that he's introduced as a capable magic user able to hold his own against Inuyasha, but is just Flanderized into being a Bratty Half-Pint and The Load. Shippo's wasted pontential is pretty prevalent in the video games where he is almost always a Game-Breaker due to his speed and vast attacking abilities.
Some fans were sad to see Koga leave the story simply because his shikon fragments were taken and would have liked to see him join in the final battle, considering he also held a strong grudge towards Naraku and had aquired another powerful weapon with his Goraishi. Takahashi may have wanted only the main characters to fight the final battle, though it appeared to come at the cost of contradicting Koga's personality up until that point as he had been just as eager as everyone else to finish off Naraku.
It's never explained why only Inuyasha can follow Kagome through time, which wastes some very interesting plots involving other characters and how they react to the present, especially with very dangerous characters like Naraku becoming a threat in the present rather than the Monster of the Week that occasionally shows up. Justified in the first movie: that the tree and the gateway that was made from it, were a sacred tree of time, so being bond to the tree, as well as being in close proximity to it is what allows Kagome and Inuyasha to travel through time. It's still a waste of a good idea though.
Similarly, one anime-only Filler depicts an attempt to create fake Shikon jewels. Being a Filler, it is never referred to again and comes off as inserted in.
For how lengthy and filled with characters and sub-plots the series is, we never get any chapters about Inuyasha's parents when they were alive, which many fans would have certainly liked to see. They did eventually have an appearance in the third movie Swords of an Honourable Ruler though.
Sesshomaru only transforms into his epic dog form a total of 3 times in 167 episodes. He doesn't need to do it every time he fights, but it would have been nice if he did it at least a little more often. Inuyasha doesn't even get a dog form probably because he's half human.
The Inu no Taisho, the third film shows how much more powerful and wiser than both of his sons, while being entirely badass as he was at his death thralls to save Inuyasha's mother. In his rescue attempt, he had used his two swords to mow down an army of soldiers and omniyoji with ease, revived Izayoi with the third, shot down with arrows and spent his last moments fighting a samurai in a collapsing buying castle. This is after suffering fatal wounds from a powerful lightning spewing dragon demon of the highest caliber that he barely managed to seal away.
Also Ryuukotsusei is this, being the killer of the aforementioned Inu no Taisho, a genuinely strong demon and was so strong that he had to be killed by his own power.
Kikyo despite her having powers and abilities that far surpass Kagome, she sacrifices herself for Kohaku in order to break a weakness for Naraku.
Toy Ship: Rin and Kohaku, Shippo and many random village girls he comes across.
The Un-Twist: "Goryomaru is Moryomaru?!" Honestly, guys? Having the same face and names differing by one letter aren't enough, apparently!
Vanilla Protagonist: Kagome, as the average modern teenager, via whom the audience mostly experiences the plot, travels through the exotic feudal-era landscape and characters she's surrounded by.
Kagome. Sometimes very justifiable, sometimes... well, not. Despite the fact that she complains a lot, if she goes overboard, she stops herself.
Another case could be made for Sesshomaru's constant dwelling on how his dad didn't give him the sword that he wanted when most of the other characters have problems that are much worse then that, even him.
What an Idiot!: Hey Kikyo, if the bad guy is unable to kill you, don't reveal it to him or you'll probably be thrown from a cliff... No, don't give him the jewel's fragments, you are only making him stronger!
What Measure Is a Non-Badass?: Fans throwing a fit because Sango dared to get married and have kids, and calling Kagome "weak" because being physically weak somehow makes you a weak person overall, even though she was just a regular schoolgirl thrust in the feudal world and she STILL gets a lot stronger as time goes on. It's averted in the actual series: Sango is a feminine, Yamato Nadeshiko family girl who is a demon slayer, and Kagura is a Lady of War that fights in a pretty kimono, her weapon is a pretty folding fan, and her attacks are all dances.