Niina Kumagaya is a Japanese voice actress born on July 18, 1963, in Osaka Prefecture, Japan. She is also known by the alias Makoto Kawahara. Her career spans several decades, with active voice roles primarily during the 1990s and 2000s.

Kumagaya has contributed her voice to a variety of anime series and original video animations across different genres. One of the roles specified is Jun Fukamizawa in the 1999 anime series Demon Warrior Koji. She also voiced the character UniPuma in the 1994 original video animation New Dominion Tank Police. In the 1994 anime Seijūden: Twin Dolls, she is credited as Ai Amatsu under her alias, Makoto Kawahara. Her filmography includes the role of Tomomi Mizuno in Dōkyūsei 2 Special: Sotsugyōsei from 1999.

Beyond the roles listed in the prompt, Kumagaya's broader body of work includes parts in other notable anime. She had a role in the long-running series Chibi Maruko-chan. In the early 2000s, she was part of the cast for series such as Tenchi Muyo! GXP, where she voiced Elma, and Kaleido Star. Her credits also include appearances in Zoids Genesis, Pokémon Chronicles, and the anime adaptation of The Beetle King, a story about forest residents.

Throughout her career, Kumagaya has worked alongside numerous other prominent figures in the voice acting industry. In the credits for Demon Warrior Koji, she is listed alongside Kōji Ishii and Miyuki Matsushita. Her professional collaborations have included working with voice actors such as Miyuki Matsushita, Kōji Ishii, Hiroyuki Shibamoto, and Rei Sakuma.