Lord of Mitsuboshi Castle in Mimasaka. He inherited the castle from his father Goto Katsukuni, ruling the seat that had belonged to the Goto clan for some 200 years. Initially serving the Amago, he later allied with Uragami Munekage of Bizen, extending control over most of eastern Mimasaka. In the Eiroku era he turned against the Uragami and sided with the Mori, holding out under siege. When Ukita Naoie expelled his own lord Munekage in 1575 and began invading Mimasaka, Katsumoto joined the resistance, but Mitsuboshi Castle fell in 1579. He fled and took his own life at Kakuresaka in Osauchi, aged 42.

A powerful figure who shifted allegiances among the Amago, Uragami, and Mori while controlling most of eastern Mimasaka. He resisted Ukita Naoie's invasion to the very end.

The 1579 fall of Mitsuboshi Castle, ending 200 years of Goto rule, is remembered as the event that marked the establishment of Ukita control over Mimasaka.