Hourou Musuko

The story depicts a young student named Shuichi Nitori, described by the author as a transgender girl, and Shuichi's friend Yoshino Takatsuki, described as a transgender boy. The series deals with issues such as being transgender, gender identity, and the beginning of puberty.

Please note that this series was 11 episodes when aired on TV but 12 episodes when it was released on BD & DVD. See "Hourou Musuko Specials."

(Source: Wikipedia)