Kamen Rider 555 is a tokusatsu television series from the Kamen Rider franchise. It follows the story of Takumi Inui and others as they become involved with the mysterious Orphnoch, a species of evolved humans threatening mankind. The series is known for its darker tone, complex character relationships, and its use of the Faiz Gear transformation system. The title you provided is a 20th anniversary sequel film, but the main/master series title is Kamen Rider 555.