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.

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.

His wartime experiences affected him greatly, as he contracted malaria, watched friends die from battle wounds and disease, and dealt with other horrors of war.

Regarding this life-changing event, a November 30, 2015, NHK announcement of his death showed excerpts of a video interview with him at age 80, in which he said that as the only survivor of his unit, he was 'ordered to die' — a prospect he considered ridiculous.

In the same interview, he explained that his Yōkai characters can be seen only in times of peace, not war, and that he purposely created these supernatural creatures to be of no specific ethnicity or nationality as a hint of the potential for humanity.

[3] Mizuki acknowledged that he considered remaining behind, but was shamed by a military doctor into returning home to Japan first for medical treatment to his arm and to face his parents, which he did reluctantly.

He has also written many books on both subjects, including an autobiography about his time on New Britain Island and a manga biography of Adolf Hitler in 1971.

In 1972 he publishes the gekiga graphic novel NonNonBa [ja] about his childhood friendship with old maid and his nanny, who impressed him with the yokai stories.

In 1991, he released a short work titled War and Japan (Sensō to Nippon) published in The Sixth Grader, a popular edutainment magazine for young people, detailing the atrocities committed by the Japanese Army during their rampage in China and Korea and is narrated by Nezumi Otoko.

From 1989 until 1998 he worked on Showa: A History of Japan, which follows the same approach and conveys Mizuki's view of the Shōwa era through a mixture of personal anecdotes and summaries of major historical events.

This changed in the 2010s when translations in several European languages of his Showa, Kitaro, Nonnonba and Hitler series began to appear, leading to an increasing interest in Mizuki and his work (and that of his gekiga peers) among Westerners.