Ryōson 了尊 (1230–1296), Shingon-line Siddham scholar of the Mt. Kōya lineage in the Kamakura period. His magnum opus is the Shittan ryaku-zu shō / Shittan rin ryaku-zu shō KR6t0420, a ten-fascicle Siddham encyclopedic compendium that is the most comprehensive Japanese Siddham survey of the Kamakura period and the last major creative work of the classical Japanese Siddham tradition before its slow decline. The work supersedes the earlier compendia (Annen, Junnyū, Myōkaku, Shinkaku) by gathering and synthesizing their material together with the late-Heian and Kamakura philological developments. The DILA authority id is A001256.