Lifespan: Tenbun 7 (1538) to 5/2 of Tenshō 7 (1579)
Title: Governor of Settsu (under one theory he also had the title of Lieutenant of Imperial Guards of the Left Division)
Bakufu: Muromachi – lord of Mitsuboshi Castle
Father: Gotō Katsukuni
Gotō Katsumoto served as a bushō during the Sengoku period.
The Gotō family resided for two hundred years (from the Nanboku period to the Sengoku period) in Mitsuboshi Castle in Mimasaka Province. Katsumoto inherited the castle from his father Gotō Katsukuni in a long line of succession.
After Katsumoto became the lord of Mitsuboshi Castle, the Amago clan of Izumo Province began to decline in power so, around 1560, he separated from their command. Together with Uragami Munekage of Bizen Province, Katsumoto participated in an attack on Emi Hisamori, a retainer of the Amago based at Kurashiki Castle. In 1562, he led Uragami forces on an invasion of central Mimasaka but the venture ended in failure. In 1563, Katsumoto incurred an attack at Mitsuboshi Castle by Mimura Iechika, but, with reinforcements from the Uragami, he warded-off the attack. Thereafter, Katsumoto kept occupied with efforts to unify eastern Mimasaka. He steadily gained influence, bringing under his command local clans such as the Andō, the Emi, and the Osakada. Eventually, he captured the majority of the eastern portion of the province.
In 1571, however, Katsumoto came into conflict with Uragami Munekage. Joining with the Mōri clan, he holed-up in his base at Mitsuboshi Castle and defended against an attack by Munekage. In 1572, owing to a settlement between the Mōri and Uragami clans, his relationship with the Uragami appeared to improve, but, perhaps because Katsumoto was removed from his position as head of the clan, in lieu of Katsumoto, letters after that time were issued in the name of his son, Gotō Yoshirō (Gotō Motomasa).
In 1575, Ukita Naoie ousted his lords, the Uragami, from their base at Tenjinyama Castle and began an invasion of Mimasaka. To oppose the advance by Naoie, Katsumoto joined with Sasabe Jinjirō, a former retainer of the Uragami and lord of Chausuyama Castle along with Hoshiga Mitsushige, the lord of Mimasaka-Washiyama Castle. However, in 1579, Naoie dispatched Nobuhara Kageyoshi as commanded-in-chief of a large army that attacked and toppled Chausuyama Castle. In the third month, the forces finally began an assault on Mitsuboshi Castle. Katsumoto fought valiantly to defend his base, but, owing to successful efforts by the Ukita to attract some of the defenders to collude as well as by setting fires, the castle fell in the fifth month. Katsumoto fled in defeat and took his own life in the hills. He was forty-two years old.
After his death, a five-part gravestone representing earth, water, fire, wind and heaven was built as his grave on the remains of Mitsuboshi Castle.