Hiromasa Yonebayashi was born in Nonoichi, Ishikawa Prefecture, Japan, and studied design at Kanazawa Art University before joining Studio Ghibli in 1962 as an in-between animation checker, where he worked on most of Hayao Miyazaki's films. He started as an animator on Miyazakis’ Spirited Away in 2001, and took up his first position of oversight on Tales from Earthsea (2006), for which he was co-director of animation. He also worked on some of the studio's short films, including Mei and the Kittenbus (2002) as animator and Imaginary Flying Machines (2002) as animation director. In 2010, he made his feature directorial debut for the studio with The Secret World of Arrietty, which was followed by two further features: When Marnie Was There (2014) and Mary and the Witch's Flower (2017).