My Hero Academia's fourth season has had its fair share of big reveals over the course of its few episodes, and one of the biggest was how All Might actually worked alongside a sidekick several years before the beginning of the series. As Midoriya officially begun his work study under this former sidekick, it turns out that the falling out between All Might and Sir Nighteye was a bit more complicated than initially expected. It was odd to see such an All Might fanboy willingly stop working with the number one hero, but it was for All Might's own good.
The latest episode of the series digs into why the two stopped working together several years back, and it all stems from a shocking prophecy in which Sir Nighteye used his Foresight quirk to predict that All Might will die soon.
After Midoriya confronts All Might about this secret, All Might reveals how he and Nighteye had a falling out after his first fight with All For One. When the fight resulted in the injury that fans had saw him with at the beginning of the series, Nighteye protested when All Might tried to immediately go back out into the field despite being so injured.
The two of them worked together for five years, and All Might decided to take a sidekick under his wing because Nighteye had admired him so much. He became the brains behind All Might's hero work, but this is where they differed. Because Nighteye used his quirk, he worried that a villain who kill All Might in a vicious way and thus did not want him to resume work so soon after being injured.
But All Might, bearing the weight of being the Symbol of Peace, worried about how the world would turn out if he were out of action. Because Nighteye protested so much, and even wanted him to pass on One For All already, All Might and he broke up their partnership due to the disagreement. Now All Might is nervous about facing Nighteye knowing that his vision of the future came to pass, and the two of them are left separated even further with their differing opinions on the One For All successor.
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 powers, even though 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 licensed by Viz Media for an English language release since 2015. My Hero Academia will also be launching its second big movie, Heroes Rising, in Japan this December.