Mizuki Yamauchi is a Japanese actress and voice actress born on September 20, 2001 in Tokyo, Japan. She is a member of the popular idol group AKB48, having joined as part of the group's 16th generation. Before her work in anime voiceover, she was active as a child actress and appeared in stage musicals including productions of Maria to Midori no Princess and The Lion King.

In 2024, Yamauchi voiced the character Hikaru Amakusa in Love Live! School Idol Musical the Drama. This project is part of the larger Love Live! franchise, and Yamauchi is one of several AKB48 members cast in the production. That same year, she also voiced Yugumo Michiru in the anime series Hoshikuzu Telepath, which is also known as Stardust Telepath. Her other on-screen appearance includes the television program AKBINGO! NEO in 2021.

Within AKB48, Yamauchi is recognized as the original ace of the group's 16th generation. She is noted as the third actress involved in the Love Live! School Idol Musical stage productions who is also an AKB48 member and, at the time of those productions, was the only one still active as an idol in the group. Her publicly listed hobbies include dancing and eating.