fella pure mitarashi-san chi no jijou the animation
Fella Pure: Mitarashi-san Chi no Jijou is a hentai manga and anime.
The story revolves around siblings Mitarai Keiko and Mitarai Noboru. Keiko is the president of the school council and is a very strict person. However, when nobody's looking, she keeps an incestuous relationship with her younger brother.