Kajita Ryuuki, born October 14, 1987 in Shanghai and raised Mie Prefeture, Japan, is a freelance writer, radio host, actor and voice actor who goes by the name "Mafia Kajita". He is most well-known for writing for websites such as 4Gamer, and mainly writes about games and anime, alongside seiyuu contents. He's also a common face on the 4Gamer Youtube channel where he mainly covers mobile games.

He is good friends with Sugita Tomokazu and Kedouin Makoto.