Aiko no Maa-chan 2nensei

Aiko Mukuno is a junior high girl who can talk to her own female organ, Ma-chan.
When Aiko starts second year, she becomes friends with her classmate Haru Omiya, with whom she can talk about her period openly, regardless of gender.
Her best friend Chizuru watches on with concern as Aiko talks explicitly about her period.
Then one day, Kikuna-senpai, a boy Chizuru has feelings for, begins to take an interest in Aiko...