I mean you could go look up who invented the philly shell boxing style/guard (or if you're a purist with far too much time on their hands you could try to dig up who started with the whole shoulder roll defense the guard is pretty much based on, but fairly sure that that's as old as boxing itself)
That's Yotsuba, right down to the impressive physical ability and being stacked, but the hairstyle doesn't match Fuutarou. Also Fuutarou has garbage athletic ability.
@Groceries fun fact: when Anderson Silva fought Forrest Griffin (my gif above was their fight), he watched Muhammad Ali tapes and when they fight, Anderson Silva finishes Griffin with a Phatom Punch, like Ali did.