Tsukasa Dōmyōji (Jun Matsumoto) and Tsukushi Makino (Mao Inoue) are driving through Nevada. Weeks prior, Tsukasa announced to the world that he was engaged to Tsukushi. He released an embarrassing picture of her eating noodles, angering her. As a result of the announcement, Tsukushi’s family become targets of media attention.
Soon after, Tsukushi’s parents formally met with Kaede Dōmyōji (Mariko Kaga), Tsukasa’s mother, to discuss the wedding. Kaede presented Tsukushi with a tiara which grants endless love to the owner and her partner. At the Hotel Volver, the couple are about to kiss when a man crashes through the window and seizes the tiara. Tsukasa pursues the thief with Tsukushi far behind, but the thief manages to escape. Tsukushi and Tsukasa return to their room, where they notice that the window has been fixed. The staff claim they heard no disturbance, even though Tsukasa and the thief have created chaos throughout the hotel. After some investigation, Tsukasa’s secretary Nishida (David Itō) informs him that the thief may be in Las Vegas. Tsukasa and Tsukushi secretly plan to go there.
Rui (Shun Oguri) phones Shizuka Tōdō (Mayumi Sada) just before her wedding. He states that he has many things to move on from. Tsukasa visits Rui to inform him of his plans. Rui asks why he did not contact Sōjirō Nishikado (Shota Matsuda) or Akira Mimasaka (Tsuyoshi Abe) instead, but Tsukasa tells him that they are busy.
Tsukushi and Tsukasa finally arrive in Las Vegas. They check into a motel before going to a casino, a location where Nishida told them the thief might be. They meet Shigeru Okawahara (Natsuki Katō), who reveals that she is seeing Kazu Kaburagi (Naohito Fujiki), the heir of a large company that owns the hotel where the tiara was stolen. Tsukasa questions Kaburagi; he says that he was told to pretend nothing happened at the Hotel- in return for his cooperation, five million USD was deposited into his account. Kaburagi claims he does not know the thief.
Back at the motel, Akira calls Tsukasa and informs him that the tiara will go on the black market in Hong Kong. Tsukushi and Tsukasa then plan to head there before Kaburagi arrives, saying that he heard about the auction. He gives them the five million to help them get the tiara back. Tsukushi and Tsukasa gamble the money at the roulette table in order to pay Kuburagi back. As the wheel is spinning, the two notice the thief and Tsukasa chases him by jumping over the table, causing the ball to land next to the winning space. The thief gets away and Tsukushi is thrown out of the casino for refusing to hand over the money. Outside, she reunites with Tsukasa and the rest of F4, who Tsukasa has called.
The five fly to Hong Kong in a private jet for the auction. They win the tiara back but Tsukushi sees Rui talking to the thief. She tells Tsukasa, but he does not believe her and the two fight. The next day, Tsukushi boards the private jet, finding Tsukasa already there. They are still on bad terms. A flight attendant serves them spiked champagne, the two pass out and the thief steals the tiara again.
They awake on an island where they wait for help. They realize that their wild goose chase around the world is similar to the story behind the tiara. After talking with Kaburagi about why he divorced his wife, Tsukushi asks Tsukasa what his dream is. He points at her. Just as Tsukushi is about to tell her dream in return, a helicopter arrives to pick them up. They arrive at an estate and confront the man who they saw at the auction. He reveals that the tiara plot is a ruse by their Tsukushi’s parents to ensure that their marriage would be happy. Everyone involved was part of the act. They finally marry in Ebisu, Tokyo.
One year later, Sōjirō is a renowned tea master releasing a book, Akira is meeting with his fellow underground men, and Tsukasa and Tsukushi are back on the uninhabited island. As they write “Love” on the beach, Tsukasa asks Tsukushi what her dream is; she places her hand over her stomach and says that it has come true. Overjoyed, Tsukasa listens to her stomach. Meanwhile, Rui has finally moved on from Shizuka as he places a picture of Tsukushi and F4 on his windowsill.