Hiro and Shiro have been friends since childhood.

Shiro has always taken care of the sweet and careless Hiro, never failing to reprimand him with verbal reproaches and light physical punishments. Now that the two are teenagers, they start to think about their future and possible separation.

With the passage of time, however, Shiro's punishments become increasingly violent and the boy seems unable to resist the impulse to hurt his friend.