The word, 'Kaisho' could be confirmed within 'the thing about pulling out a tooth' in the eighth volume of "Shasekishu" (Rasekishu) (Collection of Buddhist stories) edited by Mujo during the latter part of the Kamakura period.
鎌倉時代後期成立した無住編纂の『沙石集』巻八「歯取ラルヽ事」にも、「会所」の語が確認できる。