Minamoto no Yoritomo deeply venerated the Three Grand Shrines of Kumano and from the Bunji era (1185-1190) made numerous land donations and offerings of ancient sacred artifacts to Kumano Hayatama Taisha. The artifacts he dedicated in the Kamakura period are preserved as National Treasures in the shrine's treasure house today, representing precious evidence of the Minamoto clan's deep Kumano devotion. As the Kumano naval forces had sided with the Minamoto in the Genpei War, the Three Grand Shrines were vital political and religious allies for Yoritomo.

Taira no Shigemori (1138-1179) was the eldest son of Taira no Kiyomori and a core figure of the Heike clan, becoming Junior Second Rank and Inner Minister at a young age. Together with his father, he deeply venerated Kumano. The Nagi tree said to have been planted by him in the precincts of Kumano Hayatama Taisha has grown to approximately 1,000 years old with a trunk circumference of about 6 meters, designated a National Natural Monument. Shigemori's Nagi tree is cherished as a sacred symbol of the Kumano triad and beloved by worshippers as a matchmaking talisman.

Ashikaga Yoshimitsu (1358-1408) dedicated numerous ancient sacred artifacts to Kumano Hayatama Taisha during the Oei era (1394-1428). The third shogun of the Muromachi shogunate who led Kitayama culture, Yoshimitsu strengthened the religious legitimacy of warrior rule through his deep devotion to Kumano. His votive offerings include works representing the pinnacle of medieval crafts in lacquerware, metalwork, and dyeing-weaving, and are preserved as National Treasures in the shrine's treasure house today.