Quick answer — Ryuuho Nagaoka voices Rintarou Kai in Tamon's B-Side, Masami Oka in Let's Go Karaoke!, Linx Laulot in The Ossan Newbie Adventurer, Trained to Death by the Most Powerful Party, Became Invincible and 4 more characters.
Ryuuho Nagaoka voices Rintarou Kai (Tamon's B-Side), Masami Oka (Let's Go Karaoke!), Linx Laulot (The Ossan Newbie Adventurer, Trained to Death by the Most Powerful Party, Became Invincible), Shiraha (MAO), Mahan (DARK MOON: THE BLOOD ALTAR), Hank (Cyberpunk: Edgerunners 2), Shinichi Fuwa (Tougen Anki: Nikko Kegon Falls Arc).
Rintarou Kai is voiced in Japanese by Ryuuho Nagaoka.
