He served as a samurai at the Enryaku-ji temple, but left the capital at the age of 16 after avenging the death of his lord.

[2] He then moved to Amari Manor in Kai Province (present-day Nirasaki, Yamanashi Prefecture),[3] and was a retainer of Ichijō Tadayori.

[2] In June 1193, Gorōmaru participated in the grand hunting event Fuji no Makigari held by shogun Minamoto no Yoritomo.

According to Soga Monogatari, Gorōmaru locked Tokimune's elbows, tried to bring him down with his own weight and shouted that he had apprehended the enemy.

[2] According to legend, Gorōmaru was the lord of Tobe (in present-day Yokohama) in the Kamakura period and succeeded the former lands of the Mutō clan.

A tomb of Gosho no Gorōmaru and a monument exist in Goshoyama, Yokohama, part of the historic Tobe, but there is no further information on his activities in the area.

[2] In Soga Monogatari, it is written that Gorōmaru put a women's usuginu (a thin robe) over his haramaki armor, supposedly disguising as a woman catching Tokimune off guard.

However, the Kamakura period Azuma Kagami and the early version of Soga Monogatari do not mention him disguising as a woman; this was most likely added later for dramatization.

[10] The descendants of Gorōmaru became a prominent family in Usa, Buzen Province (in present-day Fukuoka and Ōita Prefecture), who descended to Kyushu in 1196 with Ōtomo Yoshinao,[10] the Governor of Buzen and Bungo Provinces and Defense Commissioner of the West who was also a retainer of Yoritomo.

A number of human bones were discovered near the tomb, and the area may be a gravesite of Daikyō-ji temple whose time of foundation and closing are unknown.