About half a year has passed since "Amakano 2", sets in autumn. As the seasons change, and summer approaches, a new love story is about to begin. Showing her true self as a matter of course, Yuuhi is now able to spend her age-appropriate youth together as lovers. Despite aiming for affection straightforwardly as a lover, becoming interested in her classmates, Rei's world around her has expanded a little. While attending college, acting like an older sister as before, the relationship as lovers with Chitose, continues to be deepened.

And one more, attending the school as a first-year student, a new love story with Sara. Along with this new encounter, each affection gradually grows in the dazzling summer. Eventually, this feeling becomes the driving force to take a step from just a lover towards being bounded together in the future, marriage.