Zōga 増賀 (917–1003) was a Heian-period Japanese Tendai 天台 monk, principal disciple of Ryōgen 良源 (Jie Daishi, 912–985) on Mt Hiei, and a celebrated recluse of Tōnomine 多武峯 (in Yamato Province, modern Sakurai). He was a son of the courtier Tachibana no Tsunehira 橘恒平 (a Sangi 参議). He took ordination on Mt Hiei and rose within Ryōgen’s circle but is best remembered for his rejection of court honors: the literary tradition of Konjaku monogatari shū, Uji shūi monogatari, Hosshinshū, and Senjūshō records him performing deliberately eccentric acts — riding a cow through Kyoto, refusing to participate in court rituals, displaying anti-clerical hijiri 聖 ideals — to break his attachment to fame.
After withdrawing from Mt Hiei, Zōga settled at Tōnomine, the cult-centre of Fujiwara no Kamatari’s shrine, and became known as Zōga Hijiri 増賀聖 / Tōnomine Sentoku 多武峯先徳. Despite the eccentric reputation, he was a serious scholastic: his surviving KR6n0011 Yogaron mondō 瑜伽論問答 (T2259, dated 981) is one of the earliest preserved Heian-Japanese Yogācāra study-records and a key document for reconstructing the porous boundary between Tendai and Hossō 法相 scholasticism in the late-tenth century.
DILA Buddhist Person Authority A001652. Standard study: Paul Groner, Ryōgen and Mount Hiei: Japanese Tendai in the Tenth Century (Honolulu: University of Hawaiʻi Press, 2002), Appendix 7 “Zōga as an Eccentric.”