Isaku Senagaki is the granddaughter of a family of gangsters, with an overprotective guard dog: Keiya Uto, a first lieutenant who fabricates his age to enroll in high school along with Isaku to protect her from venomous insects - men. Isaku has always thought Keiya treats her like a child, but lately, he's been acting different. She begins to wonder: "Does he actually have feelings for me...?!" Can she really be with such a dangerous man? Wanting to confirm her feelings, Isaku takes action! Could their tantalizingly ambiguous relationship finally be changing?!