Taki Kazuya, an Interpol agent living in New York City, is currently investigating a string of disappearances and murders which seem to have been caused by something inhuman. He always tells stories of his friend, a cyborg hero named Kamen Rider, who years ago in Japan brought down the evil organization Shocker, saving people from monsters and never seeking any reward for his deeds. However, the only ones who believe his tales are a group of orphans he has befriended. When one of the orphans is transformed into a monster, Taki tracks down the creature responsible and attempts to fight it in his own costume, calling himself a new Kamen Rider. However, he fares poorly against it and is on the verge of being killed. At that moment, none other than Takeshi Hongo, the original Kamen Rider, comes to his rescue. Hongo and a newly inspired Taki team up and manage to defeat the creatures. Afterward, Hongo informs Taki that a new danger is rising to threaten humanity and asks for his help before setting off to find more allies, the eight other Kamen Riders with whom he was once a team. Taki continues his work with Interpol, along with assisting Hongo's search. [Written by MAL Rewrite]

Kamen Rider Spirits is a sequel to many entries in the tokusatsu franchise Kamen Rider, bringing together characters from the franchise's first seven installments. It was originally serialized in Magazine Z and ended when the magazine ceased publication. The story was later resumed in Monthly Shonen Magazine with a sequel series titled Shin Kamen Rider Spirits. It currently holds the record for the longest running manga based on a tokusatsu show.