University student, Takatsuki Minato, likes things to be clean and in order while her stepbrother, Takatsuki Toru, is a bit of a player. One day, while cosplaying as a high-school student in a fashionable district in Tokyo, Minato accidentally bumps into Toru and quickly lies about her identity. To her surprise, Toru appears to take an interest in her alternate identity, Mina, and asks her out. Thinking that she might be able to cure Toru out of his playboy ways, Minato continues to disguise herself as Mina but will she be able to keep up the charade when she starts developing feelings for Toru?
