As a high school freshman, Nakamura Kouta has a distaste for the opposite sex. His old friend Karen, whom he hadn't seen in years, pays him a surprise visit one day. Karen is a girl who acts like a boy and uses masculine pronouns like "Boku". She enlists Kouta's help to transform her into a more girlish version of herself, so that her coworker Itsuki-san will be attracted to her. Initially hesitant, Kouta ultimately agrees to assist Karen, only to discover that teaching her how to be feminine is a more challenging task than anticipated, given his own experience as a point of reference.
