既不是大人，也不是小孩子，正处于微妙的年纪的六年级小学生绫濑花日。偶然间和同班的男同学目击了班导接吻的场面，也为了朋友的生理期来了，自己却还没，而烦恼着。另一方面，花日的朋友苍井结衣，则是悄悄地在意着一个爱欺负人的男生……

In Japan known as (12歳. ~ちっちゃなムネのトキメキ~). Base on manga series written and illustrated by Nao Maita. The anime is split into 2 season. Summary: 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 nd Yui overcome everything and find true love at the age of 12?

** Opening Theme "Sweet Sensation" by Rie Murakawa.

** Ending Theme "Cotona MODE by AOP (Member: Kei Tomoe, Yuuki Hirose, Saori Ogino, Risa Sakurana, Yui Fukuo and Aoi Mizuki).

La jeune Hanabi à 12 ans, l'âge où l'on commence à se transformer physiquement, comme mentalement. Le passage vers l'âge adulte est loin d'être facile, Hanabi découvre ses premiers sentiments amoureux mais aussi d'autres changements qu'elle ne comprend pas encore très bien.

어른도 아니고 아이도 아닌, 비명 같은 나이의 초등학교 6학년 아야세 하나히. 선생님의 키스를 우연히 목격하고, 친구보다 먼저 생리가 와서 고민하는 등 12살의 순수한 고민과 첫사랑을 그린다.