The Seven Deadly Sins aid the Sky People against a powerful group of demons hellbent on resurrecting a demonic beast sealed over 3,000 years ago.

Hanabi Ayase and her best friend, Yui Aoi, are 6th graders in school. When Hanabi is chosen to work with Yuuto Takao for an upcoming test, she begins to fall in love with him and they both start dating. Yui also falls in love with Kazuma Hiyama, after he protects her from a classmate who talked about Yui behind her back, and they start dating as well. But with physiological changes and more and more obstacles in their love lives, will Hanabi and Yui overcome everything and find true love at the age of 12?