Kyōka buys a personal care humanoid to make her life easier. Kai, her humanoid, learns everything about her, adapting himself to serve her better. Their relationship progresses, and when the impossible happens, Kyōka's 12 months of Kai exposes more than ever imagined.

In the summer of 2001, Ryo Hagio, a high school student living in a country town by the sea, is spending his last summer vacation in high school with his classmates Manabu, Kosugi, and Hotta. One day, he meets Wang Jia-ling, a foreign exchange student from Taiwan who dreams of becoming a dolphin trainer. Ryo, who hates dolphins and the ocean, is at odds with Ling, but when he learns of her true feelings about coming to Japan, they begin to have a heart-to-heart talk...