Koharu is a dull, boring girl who’s always alone. Her only hobby is building plastic models. One day, Koharu stops by a mysterious antique shop and buys a plastic model gun and a toy figure named Alice. After spending the entire night assembling the gun, Koharu wakes up to find bullets flying everywhere at school. Then she meets Alice, who moves like a human, and Alice tells her to get ready for a battle for survival called "Girl Gun Fight," where she must attack her classmates with a gun.