Hitoshi and the gang go to the beach and see a sign for a "best couple" contest with a trip to Hawaii as the grand prize. Saati and Hitoshi compete against Forty and Twenty in numerous competitions. Hitoshi wins, but it turns out the prize is just a pack of macadamia nuts. Twenty has been coming up drunk a lot, and Hitoshi is worried. He learns that she can't get a boyfriend and is very lonely. Hitoshi dresses Saati up like a man, and Saati pretends to be interested in Twenty. They go out on a date and Twenty gets Saati drunk. Saati gets rowdy and gives the whole plan away. Twenty gets mad at Hitoshi. A popular girl at school asks Hitoshi to help her with a computer program. She says she accidentally deleted several important files. Saati enters the phone lines to access the schools system. It turns out that the data the girl gives to Hitoshi contains a virus, which enhances the breast size on the records of girls in the system. Saati fights the virus with Hitoshi's help. It turns out the girl actually slipped in the virus on purpose in hope of altering her breast size data to prevent the students from finding out that she wears breast enhancing pads.
Hitoshi is obsessed with a pornographic, dating video game. He sends Forty into the game in hopes of hooking up with more girls. Forty keeps failing, so Hitoshi borrows Forty's body and goes in himself. He still fails. It turns out that Saati entered the computer game, and foiled all of Hitoshi's perverted plans. Twenty, in an attempt to end Hitoshi's perversion, creates a pair of underwear which will punish him every time he thinks about sex. If the underwear's perversion counter reaches a certain number within a day it will explode. Hitoshi aggress to wear it, but can't stop thinking about sex. Finally, it blows up and Hitoshi injures his genitals. It's Christmas time, and Saati and Hitoshi both are preparing presents for each other. Hitoshi is getting his present ready, but Saati thinks he's just playing a porno video game. Later, they tell each other that they aren't getting any presents for each other. Saati and Hitoshi fight, and Hitoshi ends up leaving the house and going out into the cold snowy night alone. Saati begins to worry, and then finds out that Hitoshi hadn't even opened the porno game she though he'd been playing.
Twenty and Forty find Hitoshi taking shelter in a phone booth. Hitoshi then plugs his computer into the phone line, and sends a x-mas message to Saati. They make up. Hitoshi and Saati go to Kikuko's mountain cabin in Aomori. They think they are alone but Twenty and Forty are actually there too, videotaping everything that happens in Hitoshi and Saati's room. Forty sees a black cat. Later, Kikuko's dad tells them that a girl killed herself, and her cat in the room that Forty and Twenty are staying in, and that the room has been haunted by the black cat ever since. Things get weird, the lights go out and Hitoshi and Saati seem to be under the black cat's spell and out to kill. In the end, it turns out that Hitoshi and the gang were playing a trick on Twenty, and trying to teach her a lesson.