Four years have passed since that emotional marriage proposal at Tsukushi Makino's high-school prom, and Tsukasa Dōmyōji announced his engagement to Tsukushi to the entire world. At an engagement dinner between their families, Dōmyōji's mother, who has been strongly against their relationship before, presents Tsukushi a tiara, which is estimated to be worth roughly 10 billion yen, as a token of their engagement. But that night, the tiara is stolen by somebody! Then, Dōmyōji and Tsukushi travel around the globe to Las Vegas, Hong Kong, and even a deserted island to get the tiara back—the legendary tiara that has been believed to "bring eternal love." In the meantime, where and what are the "F4" fellows, who have just gone separate ways, doing now?