Blue B

He was the previous jinchūriki of the Eight-Tailed Giant Ox. He did not have control over the Eight-Tails as it killed many Kumogakure ninja including Motoi's father. The Third Raikage extracted the Eight-Tails, resulting in the jinchūriki's death. The Eight-Tails was immediately sealed in Killer Bee.

Trivia

 * This person's status as a jinchuriki suggests he might have had relationships to former bearers of the title of Raikage (as per tradition) or simply a competent enough shinobi expected to use the tailed beast's power effectively, which he ultimately failed in.