555・913・2003 (555・913・2003 Faizu Kaiza Nisen-san) is the sixth episode of Kamen Rider Zi-O. It is the second part of the Kamen Rider Fourze and Kamen Rider 555 tribute arcs. Thus, it features the debut of Geiz FaizArmor.
This episode is accompanied by the sixth episode of Kamen Rider Zi-O: Supplementary Plan web series, The Secret of Fourze 555.
With Another Fourze also possessing the powers of Another Faiz, Takumi Inui appears to stop Masato Kusaka and help Sougo investigate the case. As they continue searching for answers behind the mystery of Another Fourze/Faiz's target Karin Yamabuki, they discover a connection with the Ryusei School.