We sisters have become our big brother’s personal pets.’ The sisters Rena and Aina fall in love with their stepbrother Shota, and at the same time, they end up firmly receiving his training. As he indulges in perverse play without regard for time or place, the sisters fall deeper and deeper for him… But one day, Aina receives a love letter from another boy, and Shota begins to take interest in another woman… Will the sisters’ shared relationship with him fall apart?