Mitsuru Fujimori is a young boy who appeared a month after Mukuro's defeat during the Kokuyo Arc. He was at Yamamoto's baseball game because his older brother was playing too. He was possessed by Mukuro. Tsuna felt Mukuro's presence because of his Hyper Intuition but thought that it was just his imagination, while Reborn not only noticed Mukuro, but also said that it must be tough to be alone like that and that he would take him on anytime. He has not appeared again since then in the manga or anime, but he was mentioned in the Vongola 77 character book.
Mitsuru has spiky brown hair and coal black eyes. When possessed by Mukuro, his right eye was the Six Paths of Reincarnation's 6th state. He wore a blue furry jacket and a light green collared shirt underneath.
Mitsuru, possessed by Mukuro and watching Tsuna at a baseball game from afar, quietly states to the latter that they would meet again soon. He then walks away alongside Mitsuru's mother, who is unaware that her son has been possessed.