Rei Mochizuki is a Japanese voice actress born on July 9, 1986, in Aichi Prefecture, Japan. She is affiliated with the talent agency Across Entertainment. Her path to becoming a voice actor was inspired by a childhood love for classic anime such as Sailor Moon and Yu Yu Hakusho, as well as an interest in the dubbing of foreign films. To pursue this passion, she enrolled in the Japan Narration Acting Institute to receive professional training.

Mochizuki made her professional debut in 2011, securing her first major role as Imagawa Yoshimoto in the television anime series Sengoku Otome: Momoiro Paradox. For this series, she also became a member of the associated music unit Tenka Toritai, performing theme songs. Following her debut, she continued to build her career with a variety of roles, demonstrating her range across different genres. Notable performances from this period include Anna Kaboom in Yu-Gi-Oh! ZEXAL, Juri Nakadai in Sankarea, and Rinka Tsukishima in Strike the Blood. She also voiced Kai-hime in Sengoku Paradise Kiwami and Serena Azarenka in Nobunagun.

In the mid-2010s, Mochizuki took on one of her more widely recognized roles as the zombie character Zombina in the popular series Monster Musume. Her voice acting portfolio extends significantly into the realm of video games. She is known for voicing Hinata Himezuru in the XBlaze series, multiple characters including Harugetsu and Aquila in the hit game Azur Lane, and characters in Yu-Gi-Oh! Duel Links and Quiz RPG: The World of Mystic Wiz.

More recently, Mochizuki has been the voice of the character Athena Monde across multiple installments of the Bakugan franchise. This includes the web anime series Bakugan: Evolutions, which premiered in Japan in April 2022, and Bakugan: Legends. This role represents a continued involvement in long-running and internationally distributed animation projects.

Throughout her career, Mochizuki has been involved in various collaborative efforts and group activities. In addition to the Tenka Toritai unit, she formed the voice actor unit Shunkan Realize with two of her colleagues from Across Entertainment. Beyond anime and games, her work includes performances in stage plays, radio dramas, and narration for television programs and commercials, highlighting her versatility as a performer.