Takeshi and F1, high school students, make money by stealing scooters and selling them to a delinquent gang. One day, Ayaka transfers to their school and joins their group, and the three of them decide to steal scooters together. While attempting to steal a scooter parked in a run-down apartment complex as usual, they are unexpectedly discovered by a masked woman who appears to be the owner. In a state of panic, Takeshi and the others try to escape on their bike, but
the woman, possessing superhuman physical abilities, quickly catches up to them. Yes, this masked woman is indeed the legendary slit-mouthed woman, capable of running 100 meters in 6 seconds with her mouth slashed up to her cheeks! What awaits them in their uncertain fate? And what is the true identity of the slit-mouthed woman?