Mizuki was born Shigeru Mura (武良 茂 "Mura Shigeru") in the city of Osaka, the second of three sons. He was raised in the coastal city of Sakaiminato 境港, where he spent much of his childhood as a 'scrapper': picking fights and participating in childish warfare with the neighbouring children. He displayed from an early age a particular talent for art. During his time in elementary school, Mizuki's teachers were so impressed by his skills with a pencil that they organised an exhibition of his work, and he later went on to be featured in the Mainichi newspaper as something of an artistic prodigy. In addition to this penchant for the artistic, Mizuki had an interest in the supernatural - something that was fueled by listening to ghost stories told by a local woman named Fusa Kageyama, but whom the young Mizuki nicknamed "Nononba".