The story begins one morning shortly after the Lupin gang has moved into a new hideout in Riquewihr, France. Jigen tells Lupin that the hideout's toilet is broken. Something is clogging the drain pipe. Lupin and Jigen get into a fight over the right to use the toilet in Jigen's room, which is the only other one. There is a rule in this hideout to "disguise yourself as an old person when leaving the room," and Lupin quickly disguises himself to use the toilet first. When Goemon goes out for lunch, Lupin gives him a ribbon to play the role of the "old man's granddaughter," but he ends up leaving in his usual clothes anyway. However, Goemon, who was expecting Japanese food, returns disappointed after eating a buckwheat galette. As Lupin and Jigen fight over the toilet again, Fujiko appears in the hallway. Lupin asks when she arrived, and she replies, "Yesterday, because you were drunk." Fujiko seems to know the cause of the toilet breakdown; she interrupts a call from a plumber on Lupin's phone, insisting that no outsiders be allowed into the hideout. Lupin and the others sense she is hiding something, and Lupin specifically suspects she hid something in the toilet tank. Goemon tries to confront her directly, but Fujiko pins him against the wall while naked, claiming she isn't hiding anything. Fujiko refuses to let them near the toilet, seemingly unable to retrieve the "item" yet. Meanwhile, Goemon starts making soba with buckwheat flour given to him by a cafe owner. Fujiko seems to be looking for something "long and thin" to fix the clog, but Goemon refuses to help, still holding a grudge against Lupin for using his chopsticks to clear a clog once before. Lupin confronts Fujiko about the hidden "item." He tells her, "If it's important, I'll protect it, and if it's dangerous, I'll fight with you." Fujiko seems moved by his words but says nothing. When Fujiko pleads that she needs to use the bathroom, Jigen agrees to take her. Fujiko asks with tearful eyes, "Please," surprising Lupin and Goemon with her rare vulnerability. Fujiko sneaks into the bathroom from the outside along the wall and reaches into the tank to retrieve the "item." Lupin finds a "wet package" on the table, but not realizing it's Fujiko's "item," he throws it in the trash. Outside the hideout, Fujiko recalls the events of the previous night. Because Lupin was drunk, he didn't remember when she asked about their anniversary. It is revealed that Fujiko threw Lupin's present into the toilet tank, causing the whole commotion. Fujiko mutters "Idiot" and retrieves the present Lupin threw away from the trash can.