Kuro no Shishi

A low-ranking ninja named Shishimaru is the protagonist of this early Go Nagai work, which is set in the 1500s. He seeks revenge against Ginnai Doma, an immortal samurai who has killed his fellow ninjas and who remains alive even after repeated attacks. The story blends historical elements with futuristic technology such as machine guns, lasers, robots, and atomic reactors, which are presented without explanation.