Mirumoto Yojiro was the son of the Dragon Thunder Mirumoto. After the death of his father on the Day of Thunder, Yojiro willingly ceded control of the family to Mirumoto Hojatsu, his father's adopted son, who he believed was the proper successor to Mirumoto’s legacy. Yojiro worked closely with Agasha in the maintenance of the Dragon Clan, beginning the strong bond between the Mirumoto and Agasha families that would last for centuries.