One day, Lupin finds his hotel room's toilet clogged. The resulting sanitary restriction, their need for secrecy, and Goemon's strict preference for Japanese cuisine creates friction among Lupin's gang. This is not helped when Fujiko unexpected appears, apparently let in by a drunk Lupin the previous night. While they wait for the plumber, Fujiko begins to act secretively about the bathroom, and they suspect one of her usual schemes against them. The situation becomes more complicated when a passing Zenigata is attracted by the smell of Goemon's cooking and pays a brief visit. In the end, it transpires that Fujiko had dropped by for a special anniversary between herself and Lupin, complete with a gift which she hid in the toilet's water tank, inadvertently causing the blockage.