Kōga 興雅 (d. after 1377) was a Japanese Shingon master of the Kōyasan Chū’in-ryū 中院流 transmission line in the mid-Nanbokuchō period. He was the master who transmitted the full Chū’in-ryū abhiṣeka and daiji-kanjō to Yūkai 宥快 (1345–1416), the foundational figure of mid-medieval Hōshō-in 寶性院 Kōyasan Shingon. The transmission is preserved in his sole extant work KR6t0209 Shòu Bǎo-xìng-yuàn Yòu-kuài jì, dated Eiwa 3 (1377), 5th month, 8th day. The work itself records that Kōga was at the time in failing health, transmitting the full final-and-utmost matters of the lineage to Yūkai under the awareness of imminent mortality. The DILA Buddhist person authority records him under A001131.
Surviving work in the Kanripo corpus: KR6t0209 Ju-Hōshō-in Yūkai-ki (1 fasc., 1377).