Plot

In Japan for the funeral of his long-lost love, a tough French detective learns that he also has a teenage daughter and that her life is in danger from the Yakuza.

Hubert is a French policeman with very sharp methods. After being forced to take 2 months off by his boss, who doesn't share his view on working methods, he goes back to Japan, where he used to work 19 years ago, to settle the probate of his girlfriend who left him shortly after marriage without a trace. There he mets his former colleague Momo and his daughter Yumi who he did not know was ever born. Hubert eventually finds out why his girlfriend left him and the reason becomes his and his new daughters problem.—Schwarz

A woman (later revealed to be a transvestite) dancing provocatively to the enjoyment of other nightclub patrons is abruptly hit in the face by Hubert Florentini (Reno), a commisaire of the French Police. Florentini drags her/him out of the club in handcuffs, assaulting other patrons who come too close to free the captive woman or attempt to hinder his exit. Unfortunately, one of these patrons includes the chief's son.

Hubert Florentini is chastised for the violent and unorthodox methods that he uses to accomplish his goals and is put on paid leave from the force. Despite his success and his seemingly enjoyable lifestyle of fighting crime, playing golf, and being the object of a beautiful woman's (Bouquet's) attentions, he has been unable to forget his one true love, Miko, a Japanese spy he met 19 years prior. Upon receiving news of her death, he is summoned to Japan by her lawyer, Hishibachi (Hirata Haruhiko) for the reading of her will.

Hishibashi informs Florentini that he has inherited the guardianship of Yumi (Hirosue), a fiery, adorable and eccentric Japanese/French teenage girl over whom he has custody until she reaches adulthood in two days (the age of adulthood in Japan being 20). Yumi, who was led to believe she was the result of her mother's rape and subsequent abandonment, hates her unknown father. Hubert realizes Yumi is his daughter, but doesn't tell her as she would probably flee from him.

Florentini uncovers evidence that Miko was the victim of foul play. He discovers that Miko had stolen a small fortune from the Yakuza, a fortune now destined for Yumi upon reaching adulthood. Florentini summons the help of Momo (Michel Muller), a former intelligence colleague living in Tokyo. He helps Florentini with further investigations into Miko's death and in guarding Yumi from the Yakuza by supplying him with two metal suitcases of weapons.

Yumi discovers that Florentini is her father as she is captured by the Yakuza. With the help of former intelligence colleagues, Florentini and Momo free Yumi from her kidnappers when they attempt to withdraw money from Yumi's bank account. During the rescue attempt a gunfight breaks out and all of the Yakuza are killed without any casualties to the "good guys".

Following the ordeal, Florentini takes a flight back to France, having promised Yumi he would be back in a month. But just before the plane takes off, a group of customs officers enter the cabin with two familiar metal suitcases in hand, asking for their owner.