Sayaka helps her counsin, Kanayo while she's doing her late night shift in a store. Sayaka's parent are cop so she quite used to weapon and handcuff. One night, one of their frequent mysterious customer ran into the store, with blood all over his face.
Sayaka is scared and so she uses judo move thrown the guy and handcuff him right away. Soon there are group of men who likes to scare Kanayo and Sayaka came in, asking if there's someone inside. Kanayo shoo them away.
After learning that he and his friends had been chased, Sayaka and Kanayo tries to let the man go, but they couldn't find a key. The worse thng is Sayaka accidentally handcuff herself with that man too. Kanayo and Sayaka want to ask the fire department for help but the man, Reiji refused and said that he doesn't want police to know about this and so now they have to handcuffed with each other for a while.
What should they do and why Reiji is always being chased off, and now Sayaka has to get involve with this gang fight.