Mami Koyama is a celebrated Japanese voice actress, narrator, and actress, born on January 17, 1955, in Nishio, Aichi Prefecture. She is affiliated with the talent management firm Aoni Production. Standing 155 cm tall with A-type blood, she began her entertainment career as a stage actress with the Theatre Weekend troupe before transitioning to voice acting in 1975. Her debut role was as Yayoi Kikyoya in the anime series Ikkyū-san. She was previously married to fellow voice actor Tōru Furuya from 1976 until their divorce in 1983.

Koyama is renowned in the industry for her exceptionally wide vocal range and dynamic expressiveness, which has earned her the赞誉 "seven-color voice" (七色の声), reflecting her ability to portray characters of any age or personality, from innocent young boys and girls to powerful women and even villains. In the early 1990s, she took a prolonged break from voice acting, which led to other actors temporarily taking over some of her long-running roles, though she later returned to many of them.

Her filmography is extensive and spans several decades, featuring some of the most iconic characters in anime history. One of her earliest and most defining roles was as the super-strong, naive robot girl Arale Norimaki in the original Dr. Slump series (1981-1986). This role became a hallmark of her career, and she has reprised it in numerous subsequent films and series, including cameos in the Dragon Ball franchise. Another landmark role was the titular protagonist in Magical Princess Minky Momo (1982-1983), establishing her as a leading voice for magical girl characters.

Koyama has also demonstrated a remarkable talent for voicing complex and formidable antagonists. She is widely known for her long-running role as the enigmatic and dangerous Vermouth in Case Closed (Detective Conan), a character she has played since 1996. In One Piece, she succeeded the late Fujiko Takita as the voice of the powerful and terrifying Big Mom (Charlotte Linling). She also lent her voice to the cunning Kaguya Ōtsutsuki in Naruto: Shippuden and the cold-blooded Balalaika in Black Lagoon.

Beyond these, her versatility is evident in a wide array of other significant roles. She has played strong female characters like Kycilia Zabi in Mobile Suit Gundam, Shaina in Saint Seiya, and Talia Gladys in Mobile Suit Gundam SEED Destiny. She has also portrayed comedic and quirky characters, such as Ryoko Mendo in Urusei Yatsura, the android Miki in City Hunter, and the mischievous Korosuke in Kiteretsu Daihyakka. Her voice work extends to critically acclaimed animated films, including Kei in Akira, the adult Chiyoko Fujiwara in Millennium Actress, and Chiren in Battle Angel.

Throughout her career, Mami Koyama has remained a prominent and respected figure in the Japanese voice acting world, celebrated for her profound impact and the memorable characters she has brought to life across generations of anime fans.