Ojou to Banken-kun follows Isaku Senagaki, who lost her parents at the age of five and was then raised by her grandfather Tasuke, the boss of a yakuza family. Determined not to be defined by that connection, Isaku enters high school hoping to begin again, make ordinary friends, and experience love like any other teenager. What should be a fresh start is complicated by the person closest to her household: Keiya Utou, the 26-year-old caretaker who has watched over her for years.
Keiya is so protective of the boss's granddaughter that he bribes the school administration and enrolls in Isaku's school himself, turning her attempt at a normal school life into a constant struggle for space and independence. Matters are even more tangled because Isaku is trapped in a one-sided infatuation with him and longs for that love to be returned, while Keiya sees her only as the granddaughter he helped raise. Her wish to move on becomes far more difficult as his overprotectiveness and disregard for her boundaries keep pulling her back into an unusual romance shaped by school life and yakuza-family expectations.
