Kamen Rider Black RX appears in the SD media as a super deformed version of the original hero. This incarnation presents him as a relatively new and inexperienced Rider compared to others in the SD universe, with a personality leaning toward impulsiveness; he often acts without thoroughly considering the consequences.

Within the SD storyline, Black RX develops romantic feelings for an instructor at a local sports club. This instructor becomes a target when the villainous organization Gran Shocker kidnaps her as part of their scheme to eliminate all Kamen Riders. His personal connection to the victim drives his involvement in the conflict against Gran Shocker.

For combat, he wields the Revolcane sword as his primary weapon, employing slashing attacks as his signature finishing move. His transportation is a modified Acrobatter motorcycle, adapted to the super deformed aesthetic.

He operates within a team dynamic alongside Kamen Rider 1 and Kamen Rider ZX. Kamen Rider ZX frequently teases the inexperienced Black RX, establishing a distinct interpersonal dynamic. Unlike later crossover media, only the RX version appears in this incarnation.

He maintains his core heroic role fighting against Gran Shocker's forces. Gran Shocker represents a coalition of past Kamen Rider villains united under the Great Leader's command. His actions contribute to the collective Kamen Rider effort countering this threat.