Blu is one of the two main Ultra Heroes of Ultraman R/B, and is the younger brother of Rosso and the older brother of Grigio. 1300 of years ago, he was originally a person who climbed Crusader’s Peak on Planet O-50 and was granted the Light of Ultra, but died in battle to save his siblings and was reincarnated as Isami Minato in the present day. However, he was still essentially the same person as he was before.
Blu Aqua grants him water-based abilities and improved agility.