12-sai.
English name: Age 12
Genres: Romance
Type: OVA, Episodes: 8
Aired: Apr 3, 2014 to Jan 3, 2015
Studio: SynergySP
Source: Manga
Rating: PG - Children
Synopsis:
The story begins with Hanabi, a sixth-grade girl who is neither an adult nor a child. She deals with issues such as accidentally witnessing her homeroom teacher kissing, and worrying about experiencing physiological changes before her friends. The manga depicts a 12-year-old girl's innocent worries and first love.

(Source: ANN)