When Isaku Senagaki was five years old, the death of her parents left her to be raised by her yakuza boss grandfather, Tasuke. Now preparing to enter high school, Isaku is determined to start fresh with an honest attempt at having a normal high school experience. All she wants is to be able to make friends and find love without being defined by her connection to the yakuza.

But Isaku's dreams are thwarted when her overprotective caretaker, 26-year-old Keiya Utou, takes it upon himself to enroll in Isaku's school by bribing the school administration. While Isaku yearns for a reciprocated love, she is trapped in a one-sided infatuation with Keiya, who only sees her as the boss's granddaughter he helped raise. Her longing for a normal life becomes a constant battle, and breaking free from her heart's grip is far more challenging than it sounds, as Keiya's overprotectiveness and disregard for her boundaries make it almost impossible to move on.