In Shanghai about the 1930s, Ho Tao is a Kung Fu student. His rich father has set up an arranged marriage for him with the daughter of a Japanese business associate. Ho Tao initially objects and feigns illness, but soon thereafter agrees to the marriage when he finds bride to be, Yumiko Kōda, is attractive. After the wedding, he finds out that she is also a martial artist. Ho Tao finds her style of Karate to be violent, unladylike, and potentially immodest and tries to persuade her to learn feminine but also effectual styles of Chinese Kung Fu. She is later offended during an argument over which nation has the superior martial arts styles and eventually goes back to Japan. When he travels to Japan to entreat Kung Zi to be reconciled with her husband, Ho Tao's father finds Kung Zi in training by her childhood friend and rather too attentive martial artssensei Takeno. As a ruse to bring her back to China, Ho Tao sends her a letter challenging Japanese martial arts and their inferiority to their Chinese roots. He hopes that the letter will infuriate Kung Zi enough to return to prove that her Japanese styles are as good as the Chinese ones. Once she is back in China, Ho Tao hopes to reconcile with her. But the plan backfires when Takeno reads the letter instead of Kung Zi. Takeno reads the challenge as an affront to Japanese martial arts and declares its contents with other Japanese martial arts masters who travels to China to take up Ho Tao's challenge. In the first duel, Ho Tao misinterprets a respectful gesture from the Japanese fighter and thus further antagonizes the Japanese contingent. Due to this cultural misunderstanding, the Japanese no longer treat the subsequent duels as exhibitions of their styles but rather as all-out fights. Kung Zi, seeing the gravity of the situation, helps Ho Tao by warning him of Takeno's mastery of ninjutsu. Chow Kan, Ho Tao's servant, provides a lot of the comedic relief for the film through various schemes that often bring unintended consequences for Ho Tao.
Martial arts
The film is noted for the exhibitions of various martial-arts styles and weapons:
In a departure from the norm for a Hong Kong film of that time, instead of stereotyping the Japanese characters as villains, the film portrays both the Japanese characters and their fighting skills with respect. Another unusual aspect of the film is that director Lau insisted that none of the fights ended in death. It is consistent with Lau's insistence on no characters being killed when in the film, Ho Tao criticizes the lethal technique of Ninjitsu as being dishonorable. He refers to it as an "ambush" only used by "treacherous criminals", and by contrast "the way of kung fu emphasizes on being fair and open".
