Yojouhan Fusuma no Urabari: Shinobi Hada

Shotaro, a young man who was kidnapped as a baby by a prostitute, lives and entertains in a seaside brothel. He often has to spend the night in the same room with other geishas when a rich patron takes over his room to be entertained by his favorite mistress. There he learns more about sex than many adults. So his adventures begin with both women and men.