Mafia Kajita is a Japanese writer, radio personality, and voice actor, born on October 14, 1987. His real name is Ryuki Kajita. While voice acting is a facet of his career, his primary professional identity is as a game writer and columnist for the Japanese gaming news website 4Gamer.net. He is also known for his work as a host and personality on various radio and internet programs related to games and anime.

Kajita's entry into voice acting is often closely tied to his personal and professional relationships within the entertainment industry, rather than following a traditional path. He is a long-time friend and frequent collaborator of prominent voice actor Tomokazu Sugita, a connection that has led to various media appearances and voice roles. His distinctive appearance, characterized by his height, shaved head, and sunglasses, often contrasts with his deep enthusiasm for anime and games. He has mentioned that his voice acting role as Sukekiyo in the 2025 anime Dekin no Mogura came about because the original manga author, Natsumi Eguchi, personally recommended him for the part after hearing his voice on a radio program.

Kajita has accumulated several notable voice acting credits across anime, video games, and live-action projects. In anime, he voiced the character Gurasan in the 2020 series Warlords of Sigrdrifa. He also played the role of Forest Bear in the 2017 anime Love Kome. More recently, he was cast as the store manager Sukekiyo in the 2025 television anime Dekin no Mogura. In the realm of video games, his roles include Zanzaburou in the popular mobile game Fate/Grand Order in 2021. His work also extends to live-action film; notably, he made a cameo appearance as a bodyguard in the 2016 blockbuster Shin Godzilla and portrayed the character Umibōzu in the 2024 live-action film adaptation of City Hunter.

Recurring collaborations are a significant feature of Mafia Kajita's career, particularly with a circle of well-known voice actors. He is a core member of a social group that includes Tomokazu Sugita, Yuichi Nakamura, Hiroki Yasumoto, and Nobuhiko Okamoto, and he frequently appears alongside them in various programs and events. This network has led to his participation in projects such as co-hosting the Persona Stalker Club with Tomomi Isomura, a program dedicated to the Persona video game series, of which he is a known fan. He also co-hosts a YouTube channel called Washagana TV with Yuichi Nakamura. These ongoing associations, built on his primary work in games media, form the core of his public persona and voice acting opportunities.