I feel like all of this would've worked better if he had shown up in the story beforehand. He appears out of nowhere, suddenly has all these connections to the main characters, now he says he isn't really connected to anyone (by blood) and is dead. I mean it's not awful, but it's hard to care about Izana, his redemption or sad backstory when is basically a surprise brother to one of the more important characters of the manga. Kinda like Sabo in One Piece.