J's group previously performed the theme song for the Mobile Suit Gundam: The Origin - Advent of the Red Comet anime, while Nishikawa is best known for performing theme songs for various anime titles such as: Rurouni Kenshin, Mobile Suit Gundam SEED, Valvrave the Liberator, and many more. He was previously said to perform Kamen Rider Zi-O's theme song, "Over Quartzer" due to early promotional material and a leak preview of the song surfacing online.
Kamen Rider Zero-One is set for a September 1st premiere on TV-Asahi, replacing Kamen Rider Zi-O at 9am. Lastly, more cast members for the series will be revealed on August 25th.
[via SpecialForm12]