The spring 2016 anime series 12-Sai revealed previously that it was going to get a second season which is now set to land on October 3rd, 2016.
The anime adaptation has a lengthy name attached to it as well with 12-Sai: Chiccha na Mune no Tokimeki, which is translated as Age 12: A Little Heart-Pounding.
The manga from Nao Maita previously had a short-form eight episode OVA series.