Kage no Ma ni Hana

Long ago, in the Edo period—abandoned by his master due to the two bumps which appeared on his forehead, male prostitute Shion was taken in by a doctor who grows medicinal plants for the province. Shion, both his means of earning a living and his reason to live now lost, tries to win the doctor's favor with his body in hopes of gaining a new purpose and livelihood... (Source: Houbunsha)