Kotomi Aihara is a Japanese voice actress and singer affiliated with the agency Asleben. She was born in Aomori Prefecture on May 2, 1990. Her interest in voice acting began in childhood, inspired by anime such as Cardcaptor Sakura and Hunter x Hunter, which led to a desire to portray male characters. This early interest was also influenced by her fondness for characters like Sailor Uranus from Sailor Moon, who was voiced by Megumi Ogata, an actress she came to admire.

After graduating from a local university, Aihara decided to pursue a career in voice acting following her mother's encouragement. She participated in auditions and received a special prize from the online voice-acting community Koebu. This achievement led to her being nominated in the new voice actor discovery auditions for the Seiyu Awards, where she earned a special place at the Atomic Monkey Voice Acting and Acting Institute. At the institute, she was instructed by veteran voice actress Miki Nagasawa. Aihara cites both Megumi Ogata and Shiho Niiyama as significant influences on her career.

Aihara began her professional activities in 2015 and quickly gained recognition for her first major role as Shiki Ichinose in the multimedia franchise The Idolmaster Cinderella Girls. This character, which she voices in various adaptations including the video games, anime series The Idolmaster Cinderella Girls Theater, and the web animation The IDOLM@STER Cinderella Girls: Spin-off!, became her breakout performance and a defining role of her early career. As part of this franchise, she has also performed as a singer on several music releases, including the character song single The Idolmaster Cinderella Master 038: Ichinose Shiki, which charted at number 11 on the Oricon Singles Chart in 2015.

Her voice work is characterized by a naturally low vocal register, which allows her to convincingly portray both female characters and a wide range of male roles, particularly young boys. This versatility is evident in her filmography, which includes a variety of parts such as Stola in the net anime Gundam Build Divers Re:RISE and its second season, Bamboo Memory in the popular game and anime franchise Uma Musume Pretty Derby, and Bōrinmaru Gokokuhōtenji in Tasūketsu: Fate of the Majority. She has also taken on numerous supporting and guest roles in series like Duel Masters, Beyblade Burst, Legend of the Galactic Heroes: Die Neue These, and Solo Leveling, among many others.

Beyond animation and games, Aihara is active in other areas of the entertainment industry. She has participated in numerous live concert events and stage appearances, particularly those related to The Idolmaster franchise, performing for large audiences both in Japan and internationally at events like ANISONG WORLD MATSURI in the United States. She also engages with fans through radio programs and other media. Her personal interests include a fondness for 1990s anime, horror and mystery video games, and Anisong, particularly the music of Megumi Hayashibara and Nana Mizuki.