Pyramid Game. The game by which ranks were decided in your class. A-D, A was the highest whereas F was the lowest. The one with higher ranks would get dew privileges and F ranks would get bullied. C and D ranks stand in the middle. A ranks were always privileged by different things and F ranks were bullied. In your class, that was Nishimura Riki.He even stopped participating in the game where if you don't participate, your rank will be determined as F.