Mc is a fan of erotic games and everyone knows about his about his hobby including his sister, Rena. Rena is cheeky girl who loves to tease him. One day she had to stay in mc’s house for a while because of the cosplay event she will attends. When she arrives at his apartment, the first thing mc saw was her tits, come to think of it, her tits are much larger than the last time he saw them…