Aika is a 13-year-old girl who is the heiress to her family's dojo, but she doesn't want it. She is very strong and good at martial arts, better than her older brothers Kanzen and Shouri, but she would rather be a normal girl.
She idolizes Suzuki Andre, her school's pretty boy who all the girls at school adore. However, he's guarded very closely by a group of girls who call themselves the Shineitai. Aika knows she could get through them and give Andre a love letter with her special move, the Machine Gun Special, but is afraid of Andre's reaction to such a violent girl.
Making it worse is the Yamada's rival dojo, the Panda Ryuukenpo Group, who attack at random times. However, one day, Aika finds Andre alone playing with a stray dog, and bullies appear to tease him. They're about to get violent, so Aika sticks on a bunny mask to hide her identity and saves him. Before she leaves, Andre thanks her, and after, he finds the love letter that Aika dropped. It has no name on it, so Andre wants to give it back to her but doesn't know her name or what she looks like.