A woman, who is later revealed to be a transvestite, captivates the crowd with her provocative dance moves at a nightclub. Suddenly, Hubert Florentini (Reno), a tough commisaire of the French Police, barges in and violently drags her out, handcuffed, while clashing with other patrons who try to intervene, unfortunately injuring one of them—who happens to be the chief's son.
As a consequence of his brute and unconventional tactics, Florentini finds himself on paid leave, although he generally enjoys a seemingly fulfilling life filled with crime-fighting, leisurely golf sessions, and the affections of a beautiful woman, Bouquet. Yet, despite his outward success, he remains haunted by memories of his one true love, Miko, a Japanese spy he met nearly two decades ago. When he receives the heartbreaking news of her passing, he is summoned to Japan by Hishibachi (Hirata Haruhiko) for the reading of Miko’s will.
During this meeting, Hishibachi reveals a shocking twist: Florentini has been named the guardian of Yumi (Hirosue), a spirited and quirky teenage girl with mixed Japanese and French heritage. Yumi has believed her father to be an unknown man who abandoned her and her mother after a traumatic incident, and this misconception fuels her deep-seated anger. Florentini knows the truth—that Yumi is indeed his daughter—but he keeps this revelation to himself, fearing that she would reject him and run away.
As Florentini digs deeper into Miko's past, he uncovers disturbing evidence pointing to foul play surrounding her death. It appears that Miko had been involved in a scheme where she stole a fortune from the Yakuza, a sum that would belong to Yumi when she comes of age in just two days. To protect his newfound daughter from the dangerous Yakuza, Florentini enlists the help of Momo (Michel Muller), a former intelligence associate now living in Tokyo. Momo arms Florentini with an arsenal of weapons concealed in metal suitcases, preparing them for an impending showdown.
However, the situation becomes critical when Yumi is taken hostage by the Yakuza. During a tense standoff, she comes to the heartbreaking realization of her connection to Florentini. Fortunately, with the assistance of former colleagues in intelligence, Florentini and Momo orchestrate a daring rescue, leading to an intense gunfight. In a remarkable turn of events, all the Yakuza involved are eliminated without any losses on the side of the protagonists.
After this harrowing experience, Florentini boards a flight back to France, assuring Yumi that he will return within a month. However, just as the airplane prepares for takeoff, customs officers storm the cabin, carrying the familiar metal suitcases, and request to speak to their owner, leaving an air of suspense hanging in the balance.
