Tatsumi celebrates the life and work of Japanese comics artist Yoshihiro Tatsumi. In post-war occupied Japan, young Tatsumi's passion for comics eventually becomes a means of supporting his poor family. Already published as a teenager, talented Tatsumi finds even greater inspiration after meeting his idol, famous Disney-esque animator Osamu Tezuka.
Despite his steady success, Tatsumi begins to question why Japanese comics should cater to children with cute and whimsical tales and drawings. In 1957, Tatsumi coins the term gekiga (dramatic pictures) and redefines the Manga landscape by encouraging an alternative genre for adults. Realistic and disquieting, Tatsumi's work begins to grapple with the darker aspects of life.