In 1972, Masao Maruyama founded the animation studio Mad House with Akio Sugino, Masami Hata and others. He has been involved in many phases of anime production including: planning, music, casting, and more. He is the producer of Yawara!, Card Captor Sakura, Claymore, and Death Note, and the creative producer of Hunter x Hunter and Chihayafuru, to name a few of the many Mad House titles he has had a hand in.
In 2011, Maruyama founded a new company MAPPA (Maruyama Animation Produce Project Association.) With MAPPA, he has continued producing works such as: Kids on the Slope, Terror in Resonance, and Garo: The Animation, among others.