Otama Jakushi

Mangaka who also appeared in pink films directed by Sachi Hamano. Born 1952 in Tokyo. While working as an assistant to Kimio Yanagisawa, he made his debut in Weekly Shōnen Jump under the name Isamu Yamamoto, but he grew tired of the many restrictions of working on shōnen manga, and in 1976, he re-debuted as an erotic mangaka. The reading of his pen name is intended to sound like the Japanese term for tadpole, ostensibly because of their resemblance to sperm.

Hence why the name has been left "surname" first and not romanized in the way that is standard on this site.