ULTRAMAN R/B is the first ever Ultraman series to feature two brothers “Katsumi Minato” and “Isami Minato” who transform into Ultraman.

The younger brother Isami transforms into Ultraman Blu by using a R/B Crystal and the R/B Gyro.
The basic type is Ultraman Blu Aqua, transformed using Ginga Crystal that contains the attribute of "Aqua".
Inheriting characteristics from Isami, Ultraman Blu's boldness helps him to get his first win in the battle, and he also strikes his enemies’ weak points while playing with them using his speed.