When learning of a new Java Server cyber-cafe's opening downtown, Lisa asks Homer to take her. Even though Lisa tries bribing him, Homer refuses, until Bart walks in, saying he knows a website that shows monkeys "doin' it". Homer immediately agrees to go and eagerly jumps in the car. At the Java Server, Homer nearly spends all of the family's checking account money, leaving only $1,200. Soon after, Snake walks into the cafe with a gun and cyber-robs Homer, completely emptying their account, leaving no money for their family vacation. To earn some money, Homer sneaks into Ned Flanders' house in the middle of the night, to steal and sell his possessions. Ned catches him, but rather than reporting him, informs him of a savings seminar instead, to which Homer steals his tickets. The family then attends the seminar to help solve their money problems. As the seminar progresses, it soon becomes apparent it is held by a man who, while he does point out a few useful tips, could stand to be a little less tight with his money. One of his pointers include saving money by scrounging through trash for food. The Simpsons then find out they can get cheap plane tickets by booking last-minute flights. This method comes down to booking a flight on a Boeing 707-300 with open seats, and an as of yet unknown location.. The flight they get onto, screwing over the Flanders, then heads for Tokyo, Japan.
At the hotel, Homer discovers that the Japanese are years ahead of America, having a talking toilet in the bathroom that sprays fountains of multi-colored water, while Bart discovers the TV has a camera that shows footage from the toilet. This gadget soon appalls Bart, Lisa and Marge, as Homer makes use of the multi-gadget toilet.
They start buying various things that cost a fortune there. Lisa wants to do something Japanese but Homer and Bart blatantly refuse and would rather ignore the wonders of another culture, running off when Lisa suggests something traditional. The only piece of Japanese culture Bart is willing to take in is the shows that are aired on T.V., one of which is entitled "Battling Seizure Robots" causing the entire family to collapse on the floor in convulsions. After recovering, they visit America Town, an American-themed restaurant, and then they are forced to go to the Sumo fights, Homer is arrested for attacking the emperor, whom he thought he was a sumo wrestler. After being freed from prison (where Homer and Bart learn of Japanese culture and the secret to inner peace), the Simpson family is down to their last 1 million Yen, which they need to get home. Homer folds the money into a flying crane origami to show Lisa "something Japanese", which is then blown away in the wind, Homer cries "D'oh!" in Japanese.
They try to earn money by gutting fish at the Osaka Fish Concern. While working, they see on the work TV an advert for the Super Happy Smile Time Family Wish Show, which grants the winners anything they wish for.
They go on the game show to win plane tickets back to Springfield, but go through a series of painful and humiliating tasks (most of the tasks were completed by Homer while his family watched on) including being tied to Tokyo tower during a lightning storm. To get the tickets in the final round, the Simpsons have to grab them off a bridge that's suspended above a "volcano". Meanwhile back in Springfield, Moe sees Homer on TV and he, Lenny, and Carl find out Barney was disguised as Homer to put beers on Homer's tab. Back in Japan, the Simpsons get the tickets, but learn that this task in actuality, was not a challenge, but a trap in which they bridge they are on snaps on demand and they all fall into makeshift lava which is only Orangeade loaded with Wasabi. Before leaving Homer takes advantage of now having what they wanted to harshly ridicule the host on live T.V. about how he should be ashamed of himself. Not that the host takes anything he says into account, bringing in the next contestant the second the family exits the stage. When taking off for their return trip home, the Simpsons' plane is attacked by Godzilla, who happens to also be battling Rodan and Mothra, among others. However, the family, in particular Lisa, were so exhausted from the events of their stay that they proceeded to fall asleep through the whole spectacle. Their plane wriggles free, and they return to Springfield without further incident.