This story is set in 1959 Japan. Kagi mean key in Japanese, and the story starts with key to husband and wife's diary.
Ikuko Anzai (Naomi Kawashima) is a young second wife of Souichiro Anzai (Akira Kusumoto) , but she is sexually inhibited and acts frigid ( she has great sexual organ according to Souichiro). In order to arouse his wife's sexual desire, Souichiro writes his erotic desire for his wife in his diary, and puts the key to his diary where his wife can find it so she would read it. Kenich Kimura (Mikio Osawa) is a womanizer and when Souichiro saw Kimura approach Ikuko and seeing that Ikuko has interest in him, sets them up so they would have feelings for each other. He then writes his jealousy in his diary so Ikuko would read it. He was hoping that young Kimura would act as an aphrodisiac for their sexual affairs. Ikuko also writes her emotions in her diary knowing that her husband reads it, and this play continued between the two. While at this, Souichiro's health starts to decline. Ikuko is now dating Kimura. Souichiro is believing his wife's faithfulness, but is tortured by jealousy, and gets sexually over aroused. He has a stroke while having sex with Ikuko. In his death bed, Ikuko reads her diary to Souichiro that tells the true relation between herself and Kimura. In there was written a complex form of love for Souichiro.
Unlikely story of sexual intrigue, but it's also a touching love story none the less. Ex Hikaru Genji's member (and its leader) Mikio Osawa plays the supporting role, and Naomi Kawashima although in her late 30s, shows her last nude in this movie. It's a great story driven movie based on the famous Japanese novelist Junichiro Tanizaki's novel of the same title. If you are a Japanese movie fan, this is worth watching.
