The story begins one morning shortly after the Lupin gang has moved into a new hideout in Riquewihr, France. Jigen informs Lupin that the hideout's toilet is broken, seemingly clogged by something in the pipes. Lupin and Jigen fight over the right to use the only other toilet, which is in Jigen's room. The hideout has a rule that everyone must disguise themselves as an old person when leaving their rooms; Lupin quickly disguises himself and claims the toilet first. When Goemon prepares to go out for lunch, Lupin hands him a ribbon to play the role of the 'old man's granddaughter,' but Goemon leaves in his usual clothes anyway. However, Goemon returns disappointed, having expected Japanese food only to find buckwheat galettes. As Lupin and Jigen resume their fight over the toilet, Fujiko appears in the hallway. Lupin asks when she arrived, and she replies, 'Last night, because you were drunk.' Fujiko seems to know why the toilet is clogged; she blocks a call from a plumber on Lupin's phone, insisting they shouldn't let strangers into the hideout. The men suspect Fujiko is hiding something, specifically that she stashed something in the toilet tank. Goemon tries to confront her, but Fujiko pins him against the wall while wrapped in a towel, claiming she's hiding nothing. She refuses to let them near the bathroom, seemingly unable to retrieve the 'item' yet. Meanwhile, Goemon starts making soba with flour given to him by a cafe owner. Fujiko looks for something 'long and thin' to clear the clog, but Goemon refuses to help, still bitter that Lupin once used his chopsticks to unclog a toilet. Lupin confronts Fujiko about the hidden 'item.' He tells her, 'If it's important, I'll protect it; if it's dangerous, we'll fight it together.' Fujiko seems moved but remains silent. Desperate to use the facilities, Fujiko tearfully asks Jigen to take her to the toilet. Lupin and Goemon are shocked by her rare vulnerability. Fujiko sneaks into the bathroom from the outside along the wall, reaches into the tank, and retrieves the 'item.' Lupin finds a 'wet package' on the table but, not realizing it's Fujiko's item, tosses it in the trash. Outside the hideout, Fujiko recalls the previous night. Because Lupin was drunk, he didn't remember their anniversary when she asked. It is revealed that Fujiko threw Lupin's present into the tank in a fit of pique, causing the whole mess. She mutters 'Idiot' and retrieves the discarded gift from the trash.