The Key is a story told in a diary format. Alternating between the husband's and the wife's entries. It is a he said she said take on what was going on in their life, mostly, their sexual life.
The husband and wife lack communication and instead they conceive ideas about what each of them might be feeling or thinking. All of these they put forth in writing in their diaries which they chose to write in secret but secretly, both wanted each other to read what they have written.
I did not find any of the characters likeable. At first I thought the daughter, Toshiko, is quiet, well-mannered girl. But later on, she came out rude to her parents. I also find her somewhat perverted. Setting up her mother with a younger guy which may be caused by jealousy as Ikuko, the mother, realizes in her last diary entries.
Rated this 2 stars in Goodreads. I still have Makioka Sisters to read and I'm hoping that in that novel, I will see why Junichiro Tanizaki is considered a giant in the Japanese literature.