Yoshimasu Tameru 吉益為則 (universally known by his gō Yoshimasu Tōdō 吉益東洞; sinicized as Jíyì Wéizé / Dōngdòng; zì Kōgen 公言, 1702–1773) was the founder of the Japanese Ko-iho 古醫方 (“ancient-formulas”) school and the most influential Edo-period Japanese physician. Born in Aki 安藝 province (modern Hiroshima), he moved to Kyōto in 1738 and built a major practice there. His radical clinical doctrine — return to Zhāng Zhòngjǐng alone, reject the entire post-Hàn formulary tradition (Tang, Song, Jin-Yuan, Ming) — and his abdominal-palpation diagnostic method (fukushin 腹診) shaped Edo and Meiji Japanese medicine and continue to influence modern Kampo 漢方 practice.
His principal works: Ruijuhō 類聚方 (KR3ed096) — a category-and-variation rearrangement of the Shānghán lùn and Jīnguì yàolüè formulas; Hōkyoku 方極 (KR3ed100, 1755) — the foundational doctrinal statement; Hōki 方機 (KR3ed097) — oral teachings recorded by his disciples and printed posthumously; Yakuchō 藥徵 — his polemical materia medica reducing each drug to its single demonstrable clinical action; and Idanron 醫斷論 — the doctrinal manifesto of the Ko-iho movement. His radicalism produced both a major school of followers (Yoshimasu Nangai 吉益南涯 his son, Murai Kinzan 村井琴山, Hanaoka Seishū 華岡青洲) and equally fierce critics (the gōseiha 後世派 partisans).