Narumi Rokurou is still adrift in life in his forties, unmarried, and working as an editor at a publishing company while writing hardly lucrative literary fiction. His days enjoying life at his own pace are brought to an end one summer night, when a strange twist of fate brings Rokurou together with a mysterious beauty, beginning the story of their crazed love.
As once was spoken by Zarathustra: "Everything in a woman is a riddle."

Tetsuo Aoki is a 4th year oil painter at a fine arts school. While working in an art supplies store, he meets an older woman named Akira Aizawa, who is the manager of an art gallery. Akira becomes interested in Tetsuo and she begins to pursue him when she catches him painting on the riverside. After such, their relationship begins to develop romantically. Will it develop smoothly? Or will there be unforeseen events?

Mori, a cheerful playboy in his sixth year of college, has just fallen in love with a high school girl named Hoshi. From that starting point, Mizu no Iro Gin no Tsuki portrays the relationships among Mori's friends and acquaintances.
(Source: M-U)

Nanoka and Koshiro were separated at a young age when their parents divorced. Now, 10 years has passed, Koshiro has already forgotten about his younger sister. Yet, Nanoka has decided to attend the nearby high school and came back to live with her father and brother. However, the two have met just before Nanoka came back to live together and without knowing each other's real identity, they went on a date, only to find out that they were actually siblings...