Damekko Succubus ~Henshoku na Kanojo ga Oishiku Ajiwau Ore no Are~

Kamata, a middle aged janitor for a school. He works hard but isn't well respected by the students. One day while cleaning the halls after school he comes across Yumeno Mako, one of the students. She's a gloomy girl without many friends. She says she's hungry and can't wait any longer. He tells her she should eat something and so she does. Kamata's penis!

Mako claims to be a succubus who needs human semen to live and Kamata has become her target. The lovey dovey, sweet and forbidden relationship of a middle aged janitor and student who happens to be a succubus.