Isaku Senagaki just wants to be an ordinary high school girl. But that's not an easy ask when your grandfather is the head of a prolific crime family. Further complicating the matter is her secret crush, Keiya Uto, who is her overprotective "guard dog" and lieutenant of the gang. Despite a rocky start and a few disagreements, their relationship finally blooms! The two eagerly wait for the big event on the calendar-their first ever birthday celebration as a couple...! The pair is finally getting used to life at school and at home. But things quickly take a turn for the worse when a rival gang member with a grudge against Uto shows up…