Nakazawa was born March 14, 1939, in Naka-ku, Hiroshima, Japan and was in the city when it was destroyed by an atomic bomb in August 1945.

Nakazawa chose to portray his own experience in the 1972 story Ore wa Mita, published in Monthly Shōnen Jump.

[3] This series, which eventually filled ten volumes, was based on the same events as I Saw It but expanded and fictionalized, with the young Gen Nakaoka as a stand-in for the author.

It also turned a critical eye on the militarization of Japanese society during World War II and on the sometimes abusive dynamics of the traditional family.

Nakazawa was the subject of the Japanese documentary, Barefoot Gen's Hiroshima (2011), directed by Yuko Ishida.