Demon City Shinjuku begins with a battle between former friends, the evil Rebi Ra (also pronounced Levi Ra) versus the short-lived hero Genichirou. Rebi Ra has allowed himself to be possessed in order to gain the incredible powers of evil and plans to summon demons to conquer the world. Defeating Genichirou and destroying Shinjuku, a part of Tokyo, with a devastating earthquake, the area becomes a demon-haunted wilderness. The novel doesn't have a fight scene between Genichirou and Rebi Ra. It opens with a quiet time in Shinjuku and then in a sudden change the Demon Quake hits only Shinjuku.

Ten years later, the World President, put in place to uphold world peace, is attacked by Rebi Ra with cursed plants indirectly to keep his old master, Aguni Rai, as the protector of the president, occupied. However, Rebi Ra did not know that Genichirou had a son who inherited his powers and more. After an emotional plea from the president's daughter, Sayaka Rama, the unlikely hero Kyoya Izayoi follows her deep into the heart of the evil city, finding new allies and terrifying enemies along the way. In the novel Aguni Rai asks the Information Bureau Japan Section Chief to look for Kyoya as the only one who could stop Rebi Ra.

The Section Chief tests Kyoya with a commando cyborg and then relates to Kyoya that the president is in a life-threatening curse and only has three days to defeat Rebi Ra before the president is killed as the ritual sacrifice to bring the Demon Realm to Earth, which he failed to do years prior, causing the Demon Quake. During the course of explanation Aguni Rai uses a doppelganger to communicate to Kyoya from New York in hopes of convincing him to save the world. Sayaka soon enters and pleads with him to do so as well. Kyoya finally decides to help because of Sayaka's pleas.

The film took two years to produce and had a budget of 130 million yen. It was also additionally screened in movie theaters in Hong Kong.^[5]

Hyper's Daniel Wilks criticised the film for having "only vaguely interconnected action scenes punctuated by some rather dull talkiness marred by horrible accents (the heroine is unconvincingly British and the childish sidekick speaks with a mangled Mexican drawl)".^[6]

Demon Palace Babylon is the direct sequel to Demon City Shinjuku written six years later in 1988 and follows Kyoya, Sayaka, and Mephisto as they battle against King Nebachanezzar and his four knights. This was released in the United States in a complete edition with Demon City in 2011. It was also released as two manga by ADV Manga back in 2003 and 2004. 7 novels have been published in Japan as of 2017.

Demon City Hunter is a series of 17 manga released in Japan that follows Kyoya, Mephisto, and Sayaka after the events of Demon City Shinjuku. ADV Manga published two of these in English but did not finish them.

Demon City Blues is a set of five novels that is based in the Demon City universe and has Mephisto reappearing but with a new hero, Setsura Aki. Setsura is a P.I. specializing in missing persons, but now he and Mephisto must go up against a group of vampires led by "Princess" who plan on making Shinjuku a vampire metropolis. The last novel will be released in English in March.^{[citation needed]}

The Demon City Shinjuku Role-Playing Game was published by Guardians of Order in 2000. It uses the Tri-Stat System and was written by David L. Pulver.

• Makaitoshi Shinjuku at IMDb  
• Demon City Shinjuku (OVA) at Anime News Network's encyclopedia