Relvance to Dragon Quest
In the Famicom Dragon Quest triology, he served as a scenario assistant. He also designed dungeons including the Cave to Rendarak. After Dragon Quest II released, he joked that "now I'm the most hated person in Japan".
He quited the Dragon Quest team after Dragon Quest III released. In 1991, his post-apocalyptic role-playing game Metal Max, one of the latest Famicom titles, was released. The game slogan was "of dragon-slaying has been tired", though Miyaoka personally objected as he "couldn't face Mr. Horii".