Mayumi Muroyama

Muroyama Mayumi (室山まゆみ) is the joint penname of Japanese manga artists Muroyama Mayumi (室山真弓, born 1955-08-30) and her younger sister Muroyama Mariko (室山真里子, born 1957-09-27). They made their professional debut in 1976 with Ganbare Aneko in Shoujo Comic.

(Source: Wikipedia)