The hero, orphaned when his parents were murdered, grows up to use his peculiar powers to take his revenge. The original Skull Man was one of manga's first anti-heroes, someone who would sacrifice the lives of innocents in his quest for vengeance. This darkness is what made the Skull Man so magnetic and successful.

While the TV series Kamen Rider (Masked Rider) was still in development, Ishinomori, who created that series with producer Toru Hirayama, made this manga as his own personal version, which the producers at Toei Company Ltd. used as the basis for the show. Several changes in content were made, as this 100-page one-shot story was too dark and gruesome (even cerebral) for a children's show.

(Source: Wikipedia)