Shintarō Asanuma is a Japanese voice actor, scriptwriter, and director born on January 5, 1976, in Morioka, Iwate Prefecture. He is a graduate of Tama Art University. Before becoming a voice actor, Asanuma was active as a member of the theatrical group TOON BULLETS!, where he was involved in scriptwriting and performance. His voice acting career began in 2006 when he was cast as the protagonist Kyo Sogoru in the television animation Zegapain. He was previously affiliated with Office Osawa and, as of 2012, is attached to the agency DANDELION.

Asanuma is known for a wide range of major roles across numerous anime series. He has played several long-running or iconic characters, including Takatoshi Tsuda in the Seitokai Yakuindomo series, Nishiki Nishio in Tokyo Ghoul and Tokyo Ghoul:re, Yōichi Kuramochi in Ace of Diamond and Ace of Diamond Act II, Crow Hogan in Yu-Gi-Oh! 5D's and Yu-Gi-Oh! Arc-V, and Takumu Mayuzumi in Accel World. He has also voiced protagonists in series such as the unnamed "I" (Watashi) in The Tatami Galaxy and Tatami Time Machine Blues, Izayoi Sakamaki in Problem children are coming from another world, aren't they?, and Kaito Daimon in the Phi Brain: Puzzle of God series. His other prominent roles include Leo Tsukinaga in Ensemble Stars!, Samatoki Aohitsugi in the Hypnosis Mic -Division Rap Battle- multimedia project and its anime adaptations, Hiroto Maehara in the Assassination Classroom series, and Itaru Chigasaki in A3!. Beyond anime, he is well-known as the voice of the protagonist Shulk in the Xenoblade Chronicles video game series, including its appearances in the Super Smash Bros. crossover games. His filmography also extends to live-action tokusatsu productions, such as providing the voice for Juran / Zenkai Juran in Kikai Sentai Zenkaiger.

In addition to his voice acting, Asanuma maintains a parallel career as a writer and director, a field in which he was active prior to his voice work. He has written scripts for a variety of media, including stage plays, radio programs, and anime. Notable examples of his writing work include the script for the stage play adaptation of Black Butler and scripts for bonus shorts included with the Blu-ray releases of A Certain Magical Index. He has also directed and written scripts for numerous theatrical productions under his own direction and for groups like bpm.

For his performance as part of the Hypnosis Mic cast, Asanuma was a recipient of the Singing Award at the 13th Seiyu Awards in 2019. He stands 175 cm tall and is left-handed. He has a noted professional relationship with fellow voice actor Kana Hanazawa, who requested his help with scriptwriting early in his career.