Given the circumstances, killing Akaza could have arguably come from Rengoku with his Demon Slayer Mark and polished techniques during the Infinity Castle Arc. But even if Rengoku was alive to be ...

Rengoku's true potential could never be measured since he died too early in the story. With his Demon Slayer Mark, he might have given close competition to Giyu or Muichiro. Kanroji doesn’t seem ...