Orphaned at a young age, Isaku finds herself thrust into the yakuza world under the guardianship of her grandfather. Keen on starting afresh in high school and escaping her family's notoriety, her plans take an unexpected turn when her loyal guardian, the 26-year-old Keiya, enrolls in school to watch over her. Juggling teenage life, romance, and the protective instincts of her unconventional knight, Isaku faces a tumultuous journey ahead.