Mirei Kumagai is a Japanese voice actress affiliated with Kenyu Office. She was born on September 30 in Hamamatsu, Shizuoka Prefecture. She stands 162 cm tall and has blood type B. Kumagai is a graduate of the A Team Academy and Talk Back training schools. Her career in the voice acting industry began in the 2010s. Before joining Kenyu Office, she was affiliated with 81 Produce and Ken Production.

Kumagai has built a career voicing a wide range of characters in anime television series, films, and video games. She has taken on numerous supporting and guest roles across many popular franchises. In the series Spy x Family, she provides the voice of Sharon. She also voices the character Xiuying Hong in Shenmue the Animation. Her role as Mimori Futaba appears in both the Backflip!! television series and its film adaptation, Eiga Bakuten!!. In Lockdown Zone: Level X, she voices the mother of the protagonist, Ryoka.

Her filmography includes a variety of other notable credits. In Delicious in Dungeon, she voices Marcille's mother. She played the young Nicholas D. Wolfwood in Trigun Stampede and Oddny in Vinland Saga. She has also had roles in long-running series such as Jujutsu Kaisen, where she voiced an Assistant Supervisor, and Sword Art Online. Her work extends to the Pretty Derby franchise, where she has voiced audience members.

Beyond anime, Kumagai is active in dubbing foreign content and video games. She provided the Japanese voice for Shuri in the video game Marvel's Avengers and for Tempest Shadow in the Japanese dub of the film My Little Pony: The Movie. Her other video game roles include Sakoora in Makai Senki Disgaea 7 and Rie Shibuki in Ryu ga Gotoku Online. She also voiced characters in the Japanese dubs of series such as Love Alarm and The Super Mario Bros. Movie.

Kumagai possesses a range of skills, including sword fighting and iPhone repair. Her hobbies include cooking and mountain climbing. She speaks the Enshu dialect of Japanese. In 2023, she married fellow voice actor Toru Sakurai.