Out of all the villains My Hero Academia has to offer, the Hero Killer Stain stands out. Despite having little screen time, he's managed to leave a lasting impression on the characters and on the audience. His influence is so great and has frightened many characters, even the Number Two pro-hero Endeavor. Let's take a look at Stain to see how this memorable villain is effective in striking fear into the hearts of heroes and fans alike.
Who is Stain?
The Hero Killer Stain, whose real name is Chizome Akaguro, is known for killing and permanently disabling many pro heroes, including Tenya Iida's brother Tensei. Stain's Quirk is called "Blood Curdle" and allows him to paralyze his victims after ingesting blood. The length of time he can keep his opponents paralyzed depends on their blood type. The order of most to least resistant blood types pertaining to Stain's quirk goes O, A, AB, B. People with O blood will recover the quickest from his paralysis, whereas people with B blood stay paralyzed for the maximum limit of eight minutes. This might be because Stain's own blood type is B.
Stain carries with him a katana, five daggers, throwing knives and folding knives to make his job of obtaining his opponent's blood easier without getting too close. This also compliments his close combat fighting style. He has incredible speed and endurance, which is how he has been able to evade capture for so long and his villain name derives from his idea that someone needs to be stained in blood to take back what it means to be a hero.
From Hero to Villain
Similar to protagonist Izuku Midoriya, Stain was greatly inspired by All Might's hero debut and was encouraged to become a hero. However, after enrolling into a hero course, Stain realized the unjust reasons as to why many wanted to become heroes. Unlike All Might, some just wanted to be a hero for the money and glory, instead of dedicating themselves to doing something good. The negative aspects of the hero world consumed him to the point where he dropped out of the course all together. He began preaching his ideology on the streets for the next few years, trying to bring back the original philosophy of heroics, but no one ever listened. Once reaching his late teens, Stain realized that words are powerless without actions and spent the next decade training in killing techniques to fulfill his ideology on his own.
Stain's mission emphasized the old philosophy of heroes as he believed true heroes should not seek compensation for their efforts and that the title of "hero" should only be given to those willing to self-sacrifice. The negatives of the current hero society have consumed him as he believes it is completely filled with fakes and must be purged. He makes an exception for All Might, who he deems the one true hero in this society. Stain eventually sees the same self-sacrificing traits in Deku and holds back, refusing to kill him. Deku becomes the second person to be deemed as a true hero in the eyes of Stain. When Deku is whisked away by a Nomu, it is Stain who risks his life to save the young hero despite his major injuries.
Stain's Legacy
Stain is a villain completely dedicated to his philosophy. However, after rejecting Shigaraki's beliefs, his brief association with the League of Villains drastically increased their popularity, later leading to the partnership with Overhaul and recruiting more members like Toga, Dabi and Spinner. Stain is now locked up in the Tartarus prison, but his beliefs have influenced a great number of people who agree with him. For example, Spinner completely adapted Stain's way of thinking, even stopping Magne from hurting "true hero" Deku during the training camp arc in Season 3. Dabi also adopted Stain's philosophy, but has his own twisted version of it as seen in recent chapters of the manga. His impact also motivated Shigaraki to alter his ways of villainy by developing a fundamental reasoning for his cruel acts.
Despite only appearing in the series briefly, Stain's influence is powerful and still plays an active role within the lives of the characters. He is still alive, but it is uncertain if he will make another appearance. For fans rooting for his return, it is worth noting that there are a few unanswered questions that we would like to be addressed. His parents' deaths were considered non-criminal, but how did they die? Did their deaths effect Stain further? Who created the video showcasing Stain's backstory and how did they know so much about him? How will his ideals continue to effect heroes and villains alike? Why is his nose carved out? How would he react to Uraraka, who became a hero for money, but to help her parents?
He wanted to showcase the truth of current heroes, but accidentally contributed to the increase of villains and injustice. Deku mentions to Shigaraki that he understands Stain's ideals, but cannot agree with his methods. Stain's role in the series alters the naive viewpoint some might have on the hero and villain society, exhibiting how flawed both societies really are. People aren't merely heroes or villains and are much more complicated than just that. What makes Stain stand out is that his violence has a cause and a deep philosophy behind it. Just like Deku, even if viewers don't agree with his violent methods, they can see there is truth behind his beliefs, making Stain is a character falls on a grey moral spectrum.