- A vivacious, aggressive, instinctive, and devilish younger sister "Aira" and a slightly more mature brother. Aira, who loves her brother and is irresistible, becomes more excited and burned the more she thinks that "there is a line that should never be crossed". - Aira uses that hand to seduce her "serious" brother with an insane provocation and fall! Gradually, the brother's reason collapses, and in the end, he is made to do as the "little devil" sister wants.