Age: 18 Pilots the R-1. Rank: Second Lieutenant. A psychodriver and an upbeat young man who happens to be a massive robot otaku. He is friendly and sociable, though he has a habit of converting everyone around him into mecha otakus. His naming sense for special moves is notoriously bad. His nickname is Ryu. His R-1 combines with Rai's R-2 and Aya's R-3 to form the SRX.

Age: 19 Pilots the R-2. Rank: Second Lieutenant. The second son of the prestigious Branstein military family. He is generally cool-headed and composed. Due to a past accident, his left hand has been replaced with a prosthetic. He and Ryusei became close friends after a period of constant bickering. His older brother, Elzam V. Branstein, is the captain of the Kurogane. His nickname is Rai.

Age: 21 Pilots the R-3. Rank: Captain. Mai Kobayashi's older sister. Aya is also a psychodriver. She was previously in a relationship with her superior, Ingram Prisken, and has been emotionally devastated since his death. Normally, she has a refreshing and straightforward personality.

Age: Mid-20s Pilots the R-GUN Powered. Rank: Unknown. Aya's younger sister. She carries the weight of her past actions as Levi Tora during the L5 Campaign. While naturally gentle, she has become significantly more timid recently. Mai is also a psychodriver and harbors feelings for Ryusei. Her unit, the R-GUN Powered, serves as a weapon for the SRX to fire the HTB Cannon (Hyper Tronium Buster Cannon).

Age: 20s Pilots the R-GUN. Commander of the SRX Team. Compared to her past self, she has become more expressive with her emotions, showing a more human side and occasionally having moments of clumsy silliness.

Does not participate in conversation (Deceased). Already dead at the start of this scenario. He was one of the key figures who led the SRX Project but was brainwashed by Euzeth Goetz during the L5 Campaign and ultimately died.