The Night of the Earthquake.

Mari and Yasuo are getting "fresh" with each other at the garbage dump when Mari unveils that she knows the whereabouts of a safe holding $100,000. After some convincing, Mari gets Yasuo to help her with the robbery. What these two sexually charged criminals don't know is that Kawada, a sadistic accountant for his gang, is also after the cash, and will stop at nothing to get it. During the night of the robbery, Katsuhiro, the manager of the warehouse in which all of this takes place, checks in the office only to find his co-worker and lover Keiko all tied up by the hands of Mari. Kawada arrives soon after, and as he's about to gut Yasuo like a fish, a massive earthquake shakes the whole city, and everyone is trapped inside. Kawada takes over and maniacly ties everyone up and carries out his savage sexual fantasies.