Keisuke Koumoto is a Japanese voice actor born on November 18, 1986, in Tsuyama, Okayama Prefecture, Japan. He is affiliated with the talent agency Production Ace. His path to becoming a voice actor was unconventional; he originally aspired to be a lawyer and even attended a trial observation. However, after watching the anime series Mobile Suit Gundam SEED on a friend's recommendation during his second year of high school, he decided to pursue a career in voice acting. He enrolled in the voice actor department of the Amusement Media General Academy in Osaka to train for his new career.

Koumoto made his professional debut in 2007. Early in his career, he was a member of the voice actor unit Boy's Beat. He was initially affiliated with Aoni Production before becoming a freelance actor and eventually joining Production Ace.

Koumoto has built a diverse filmography across anime, video games, and foreign language dubbing. In anime, he has taken on a range of supporting and lead roles. He played Raul Chaser in the series I Couldn't Become a Hero, So I Reluctantly Decided to Get a Job, which was his first lead role in a television anime. Other notable anime roles include Tazuki Kamiya in How to Keep a Mummy, Nozomu Nanashima in Kiss Him, Not Me, Kyōtarō Azuma in Tokyo ESP, and Shinichirō Asano in Isuca. He has also appeared in long-running series such as Boruto: Naruto Next Generations, providing the voice for Kagura Karatachi.

In the 2010s, he was a regular in the Cute High Earth Defense Club franchise, voicing Akihiko Beppu in multiple installments, including Cute High Earth Defense Club LOVE! LOVE! and Cute High Earth Defense Club LOVE! LOVE! LOVE!. His work in the late 2010s and 2020s includes roles such as Shōma Akiyama in Hensuki: Are You Willing to Fall in Love With a Pervert, As Long As She's a Cutie?, Julius von Littenheim in Wise Man's Grandchild, Hughes in By the Grace of the Gods, and Ruka Nazumi in VazzRock the Animation. He also voiced Marker Clan in the 2022 film Mobile Suit Gundam: Cucuruz Doan's Island, a role that connects back to the series that inspired his career.

Beyond anime, his work includes voicing Joe Shimamura / Cyborg 009 in the 2017 series Cyborg 009: Call of Justice and Serge Liebert in the game Valkyria Chronicles 3: Unrecorded Chronicles. He is also active in dubbing foreign films and series into Japanese, providing, for example, the Japanese voice for Anakin Skywalker in Star Wars Battlefront II.

Koumoto has also participated in radio programs and music projects. Notably, he was a personality on the radio show Binan Kōkō Chikyū Bōei-bu Love! Love! ☆Radio☆The☆VEPPer☆ alongside fellow actor Yoshiki Murakami, which was based on the Cute High Earth Defense Club series. The program received recognition, winning the third Aniradi Award for Best New Program and the fourth Aniradi Award for Best Male Radio Program. He has also performed theme songs for anime, such as the opening theme Prince×Prince for Kiss Him, Not Me as part of a group with fellow cast members. His career reflects a steady trajectory of versatile performances across various media in the Japanese entertainment industry.