Tanzo was a Japanese priest and intendant of Shingu Shrine in Kumano (Wakayama Prefecture).
Tanzo was born about 1130.
He bore malice against the Taira, and followed the Genji Clan. At the battles of Yashima and Dannoura, Tanzo led naval forces and helped to destroy the Taira. It is said that the victory of Genji over Heike owed much to those followers of Tankai from the Kumano District.
Tanzo married his sister to Tadanori Taira and entered into blood relationship with Taira family, becoming a powerful figure.