Part 1:
Umi has always harbored feelings of inferiority towards Tougo, a diligent student. They end up dating after Tougo confesses his feelings to Umi, and moved by Tougo's willingness to do anything for his lover, the two build a sweet and loving relationship.

Part 2:
The two of them go on with their normal student life. Tougo, who is usually always on top of everything, gets surprisingly depressed over something trivial. This is the story of Umi, who lusts over him.