Narasakicho is a site-spot near the seashore. In this town, there are two mysterious phenomena. One of them is a rainbow over the town, it doesn't disappear. Whenever one looks up, it is always there. The other one is a magic called "Gift". It is a present that one can give the other only once.

Amaumi Haruhiko is a student who goes to Shimano Academy. One day, a student transfers to the school. It was his sister-in-law. She used to live with him, but they have been living separately by some reason.