Nooo!!!! the coach was cool, he didn't deserve to die
Also with hyouma sister i think is uncertain, she can either continue boxing (on father memory), quit boxing (and probably turn into a delinquent, hikikomori or something like that) or if his father death was an accident (car probably) maybe she's on coma/wheelchair or broken arms.
And watari must be insane, he was the one that liked the coach most.
On another note, if isamu is the school swiming star and keeps being the smartest one, moka must get back on boxing quick to protect herself from the fangirls attacks
