is a Japanese voice actor from Kanagawa Prefecture, Japan. He is affiliated with and representative of T's Factory, a voice acting agency he founded in October 1998. His son is , a fellow voice actor. Koyasu has taken over many of the characters played by Kaneto Shiozawa after his death. Career When Koyasu was in junior high school, he, as an aspiring screen actor himself, was such a movie buff that he would watch movies every day without going to school. By chance, he saw the scene before Tetsurō Hoshino's departure in Adieu Galaxy Express 999 where a group of nameless soldiers take him on the 999 and send him on his way, and was impressed by it. This sparked his interest in voice acting, and since then it has been his policy to aim for "three-dimensional acting." After graduating from high school, he entered a training school. In 1988, he made his voice acting debut in Wowser, and in 1989, he played his first regular character as Gai, the King Yaksha in Legend of Heavenly Sphere Shurato. Although he was a regular character in the series, he was in the position of a villain whose inner workings were rarely discussed in the story, so it was difficult for Koyasu to grasp the role and he had to do several dozen retakes for a single line. He later said that although his name recognition as a voice actor had increased, he did not feel like he was doing his best. Afterwards, Koyasu played the role of Minos in the OVA Aries released in 1990. The OVA was based on a fantasy manga of the same name that was being serialized at the time, and the voice actors for the main characters were to be decided by a magazine reader's vote. Since Koyasu had appeared in Shurato shortly before this, he had some recognition among the viewers, and he received the most votes for the role of Hades, the main character. However, at the time, Koyasu was still an unknown name in the voice acting industry, and the production members voiced their concerns about giving the lead role to a newcomer like Koyasu. As a result, the results of the readers' poll were rejected, and Koyasu was given the role of Hades' subordinate Minos, a role with little screentime. In Tekkaman Blade, Koyasu played the main character's rival, Tekkaman Evil (Shinya