Mizu Arai is a Japanese voice actress also known by the stage names Ako Mayama and Rin Mizuhara. She was born Yasuyo Kawando on November 15, 1958, in Toki City, Gifu Prefecture. She is a graduate of Gifu Prefectural Tajimi Kita High School and Toyo University. Arai was formerly affiliated with the talent agency Production Baobab and is now associated with Kenyu Office. Since around 2003, she has performed under the name Rin Mizuhara.

Arai began her voice acting career in the late 1980s. One of her early roles was the five-year-old version of Kazuko Yoshiyama in the 1983 live-action film The Girl Who Leapt Through Time, also known as The Little Girl Who Conquered Time.

Throughout her career, Arai has portrayed a wide range of characters, often specializing in young boys, middle-aged women, and elderly female roles. Her extensive list of anime television credits includes Rantaro's mother in Nintama Rantaro, Miss Double Fingers, Kokoro, and Granny Nyu in One Piece, and numerous characters in Detective Conan, such as a landlady, Shinobu Katagiri, and Mizu Kusano. She has also performed in the Gundam franchise, as well as in The SoulTaker, Ghost in the Shell: Stand Alone Complex, Cowboy Bebop, The Law of Ueki, Yu Yu Hakusho as Mayuri, and Yes! PreCure 5. Her film work includes roles in the theatrical film Ninja Hattori-kun, the animated film Hal, and a voice role in the original video animation One-Punch Man.

Arai has made notable contributions to several long-running series, including lending her voice to characters in The Gokusen, Hell Girl, Honey and Clover, The Twelve Kingdoms, and Zatch Bell!. She is recognized for her distinctive voice, which is often described as husky and similar to that of fellow voice actress Hisako Kyoda. Beyond her voice work, she practices the traditional Japanese art of kouta, a style of short songs, under the name Ritsu Tachibana.