Isaku lost both her parents in a fatal car accident when she was a mere five years old. Little did she know that she would be taken under the care of her yakuza boss grandfather. As she grew up, she faced social ostracism due to her family's criminal background. When she enters high school, however, she decides to lead a normal life and even find love. Her plans are disrupted when her loyal family guardian and servant, Keiya, enrolls in the same school to protect her. Along with navigating high school, Isaku also has to deal with Keiya, who is constantly smoking and carrying a gun. How will she cope with this unexpected twist of fate?