Sono is a newcomer at school who unexpectedly finds herself in the midst of a group of outcasts called the "BxB Brothers," which stands for "Baka Brothers" (meaning "fools" in Japanese). This group is all about living life outside of the norm. While Kazuhisa and Kei are happy to welcome anyone new, Katsumi is more fastidious. The current members consist of only the three of them, until Sono impresses Katsumi with her atypical character and is invited to join. Sono gradually assimilates into the BxB Brothers and their values. However, as the only female in the group, she faces challenges. Kazuhisa is openly affectionate towards her, but Katsumi shows more reserved admiration (with Kei keeping an eye on their relationship), and the club is still struggling to become official. This love triangle is constantly changing, adding further complications to the BxB Brothers' story.