Meet Chisato Mashiro, an outwardly typical young girl who only thinks about boys and dating her sempai. Normally a quiet, obedient girl, she goes through her rebellious phase, and often the target of her outbursts is her uncle, who is upset that the once cute little girl who always played with him has become so profane (although he has nothing against some of her parts, also growing up with her) One day Chisato catches her uncle rummaging through her underwear drawer, and being furious about it, she unleashes a torrent of verbal insults and threats realizing that her uncle has overstepped his bounds. He, in turn, decides that he has had enough of this behavior, and decides to take matters into his own hands and take a more active role in raising his beloved Chi-chan.