Mayumi Muroyama (室山 まゆみ Muroyama Mayumi) is the joint pen name of Japanese manga artists Mayumi Muroyama (室山 真弓, born August 30, 1955) and her younger sister Mariko Muroyama (室山 真里子, born September 27, 1957). They made their professional debut in 1976 with Ganbare Aneko in Shōjo Comic.
In 1977, Muroyama published Asari-chan, which was collected in 100 volumes and which had sold 26,500,000 volumes total as of May 2006, making it the seventh best-selling shōjo manga ever in Japan. Asari-chan received the 1986 Shogakukan Manga Award for children's manga. Several of Muroyama's manga have been adapted as anime, including Asari-chan as both a television series and theatrical movie, Dororonpa! as a television series, and Mr. Pen Pen as a television special.