The two main characters, Katsumi and Isami Minato, are brothers who live with their younger sister and father who runs a specialty store. One day, they found the R/B Gyro and R/B Crystals, which transforms Katsumi into Ultraman Rosso and Isami into Ultraman Blu.

Yuya Hirataas Katsumi Minato / Ultraman Rosso
Ryosuke Koikeas Isami Minato / Ultraman Blu
Arisa Sonoharaas Asahi Minato
Ginnojo Yamazakias Ushio Minato
Kaori Manabeas Mio Minato
Kaede Yuasaas D.R.L.N. (voice)
Motoki Fukamias Makoto Aizen / Cereza
Ayane Kinoshitaas Saki Mitsurugi / Grigio
Kiara Minegishias Isami Minato (Young)
Toshizo Nemoto
Aya Satsuki