When Marge becomes obsessed with a Japanese style of living, the Simpsons must part with any item that no longer brings them joy. For Homer, this means finding a new home for the family pig. For Lisa, it means saying goodbye to her beloved sax.
Several monks are handcrafting the book The Japanese Warrior Monks Guide to Tidying Up, a book to teach people to reach "the state of enticement", carefully when they were told that America had ordered a shipment of one million books. When they find this out, all the monks are fired and robots make the books in a factory instead. When one of the robots was told it had put two front covers on the book, it committed seppuku.
The Simpsons go to the Springfield Car Wash, and Marge buys the book. Homer buys some sushi and ends up going to the hospital.
The family reunites at home and she makes the family follow its teaching, giving up everything that didn't give them joy any more. Lisa gives up some of her Malibu Stacy dolls, Bart tells Marge all his stuff gives him joy, while Homer gives up his Mr. Plow's jacket.
Marge however tells him he has to give up Plopper, and to find him a new place to live, so he puts an announcement on Greg's list. The first one to offer it is Snake, but Homer refuses, getting in a panel van to navigate back home.
Bart, Lisa and Homer with Plopper go to Luigi's and see Joyce Carol Oates at a table, but when trying to enter with the pig, Luigi forbids them, unless Plopper becomes a therapy animal.
Homer prepares to make Plopper one, but Lisa gets worried of him getting in trouble and gets an anxiety attack, and Homer gets the idea to get a prescription for anxiety at Dr. Bud's Medicinal Marijuana Clinic, but he turns out to be a mountebank, so he turns to Dr. Nick, which gives him some pills.
Lisa gets rid of every object in her room, and finds out the sax doesn't give her joy anymore. Meanwhile Homer brings Plopper at the Power Plant, placing him on his seat, and says to Marge that he'll bring him everywhere he goes so she won't see it for long anymore.
At the Springfield nuclear family day picnic, Lisa gives up her sax, while Plopper gets greased up by kids, and the Hounds attack him, biting his back's ribs. Dr. Budgie visits him, and to avoid a lawsuit, Mr. Burns and Smithers agree to take care of him.
Back at home, Lisa is empty of any joy since she gave away all of her stuff, so Bart helps her at school, playing the music she likes over the intercom. She gets her joy back, but is missing her stuff, so Marge takes her to Springfield Lock 'N' Leave Storage Facility and reveals she kept all the stuff there, and go and retrieve them, disturbing Gil.
At Burns Manor, Dr. Budgie gives Plopper a makeover, and Burns have some great moments with it. Homer comes to check on him and sees Burns dancing with it. He then returns to the manor that evening and gets back his animal friend, and to keep him he says to Marge he will give up beer.
That night, Homer has a dream of a Hellman's mayonnaise cartoon, similar to one he had early, and wakes up from the nightmare after seeing they prepared hamburgers with fruit in the sides.