They took his family, they took his face, and they took his soul. Locked between the lethal but gorgeous assassin Maria and the mutant Spider Man, the Skull Man digs into the conspiracy that gave birth to his powers and those of his partner, Garo. Haunted by his past, he will not let them stand in the way of his revenge. 
(Source: Tokyopop) 
Multiple Shotaro Ishinomori heroes make cameos, Kamen Rider 1 and Joe Shimamura (Cyborg 009) have the most. Other cameos include Himitsu Sentai Goranger, Kikaider, Inazuman, and Robot Keiji.

Otomo City: where freedom and justice have atrophied to the bone; where conspiracy rules the day and death stalks the night... Death in the form of the Skull Man, a literal Grim Reaper whose skeletal grin presages grisly mayhem and murder, even to the monstrous mutants that haunt the city's underworlds! 
To investigate a bizarre slaying, journalist Minagami Hayato and photographer Kiriko Mamiya must stalk this ultimate predator, through a festering cadaver of a city where the corruption flows in rivers as deep and foul as the sins of the reigning elite, and unearth a secret so shocking that an entire city has been turned into a tomb to contain! In a nightmarish necropolis where nothing is as it seems, vengeance comes in the form of a living Death's-Head! 
(Source: Sentai Filmworks)

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)

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