Warning: SPOILERS for My Hero Academia Season 6 episode #131Episode #131 of My Hero Academia shows that, despite everything that he's gone through since he became a trainee hero, Deku can still make huge mistakes. His decision to abandon his friends and the safety of U.A. High is a dramatic one, and it leads straight into the new phase of the story: the Dark Deku Arc.
After the disastrous conclusion of the Paranormal Liberation War, Deku fell into a coma. His body has healed, but the long sleep was a chance to meet all the vestiges of the previous users of his Quirk, One For All. In episode #131 of My Hero Academia, after discussing with them the origins of his power and the reason why All For One is trying to steal it, Deku decides that the best thing to do is to leave everyone behind. He writes a farewell letter to each of his friends and classmates, explaining the truth about his Quirk, and leaves U.A. High, hoping that, in this way, All For One will not put his friends in danger. Deku becomes a lonely and tormented vigilante, but this decision proves to be a huge mistake.
Deku's Guilt And Sense Of Duty Is Pulling Him In A Dangerous Direction
Manga readers are already familiar with the developments of the Dark Deku Arc, which will begin next in the anime, as teased by the final scene of this episode. However, what is most shocking is that Midoriya could actually take the decision to leave everyone behind. Clearly, he feels a huge responsibility, as the ninth user of One For All, to defeat All For One, and he thinks that this duty, and the dangers that accompany it, belongs to himself alone. Another reason is that Deku feels guilty for not being able to stop Shigaraki during the Paranormal Liberation War. He feels responsible for everything that happens during and after that battle, including the deaths of many Pro Heroes and the terrible injuries suffered by his teacher Aizawa and his friends Bakugo and Shoto.
While Izuku's feelings in that regard are understandable, his decision to go solo is not. Before learning the truth about One For All and accepting his duty as the ninth successor to that power, Deku was Izuku Midoriya, a kid who wants to be a hero among everything else. He should know that heroes never leave anyone behind, and that includes his friends, who now think he considers them a burden. Also, while Deku's mastery of One For All and its Quirks will improve over the lonely time that awaits him, it's impossible to even think of defeating All For One and his huge army of villains alone, without the full support of the Pro Heroes and the authorities.
After everything he went through since acquiring One For All, Deku should really know better. Instead, he lets his sense of guilt cloud his judgment and starts on a dark and dangerous part. My Hero Academia's Dark Deku Arc is the gloomiest of the entire series, and it will show if Midoriya's friends and mentors will be able to pull him out, or if Deku's mistakes will prove to be his undoing.
Season 6 of My Hero Academia is streaming on Crunchyroll.