Hero Killer Stain's introduction into My Hero Academia greatly changed the landscape of the series as his fiery passion swayed both the hearts of heroes and villains. It turns out that he's still being felt all this time later.
As the only Shiketsu student who didn't make it to the second round, he's begun giving commentary on the Rescue Exercise. His teacher says he should use the moment to reflect on what happened, as he's been influenced by the words of Hero Killer Stain. Seiji thinks the idea is absurd, but his teacher argues that it may not necessarily be a bad thing.
Arguing that Stain's fundamentalist ideals and All Might's retirement have sparked others into wanting a major reform of their current hero society. But he warns Seiji that if he lets his hatred and negativity become his sole driving force it can lead to him clouding his judgment and even going too far much like a villain would.
It's frightening to think that Stain's words still have an effect so much later after his appearance, and it's even more so after All For One fought All Might and revealed his weakness to the world. Although Seiji didn't realize it, he lost the first test of the exam because of a blind rage he had toward Class 1-A.
When he came across Bakugo, Kirishima, and Kaminari in the first exam, Seiji was able to temporarily subdue Bakugo and Kirishima but was outsmarted by Kaminari. This was because Seiji was stuck in his own sense of self-importance, as he kept berating them for their lack of what he perceived as true heroic qualities.
It's the same thing that Hero Killer Stain was in search of during his rampage, and this conversation just goes to show just how innocently these dark thoughts can begin.
My Hero Academia was created by Kohei Horikoshi and has been running in Shueisha's Weekly Shonen Jump since July 2014. The story follows Izuku Midoriya, who lives in a world where everyone has super powers but he was born without them. Dreaming to become a superhero anyway, he's eventually scouted by the world's best hero All Might and enrolls in a school for professional heroes. The series has been collected into 19 volumes so far, and has been licensed by Viz Media for an English language release since 2015.