The conjugation system in bungotai (Japanese literary style), relating and ending rules, and distinction in forty seven kana (characters) that are taught in 'kobun' (Japanese classics) of Japanese language (subject) education, were based on the middle of the Heian period, and it can be said that it was during the Insei period that they started to collapse.
日本の国語(教科)教育の「古文」で教えられる文語体(日本語)の活用体系や係り結びの法則、47文字の仮名(文字)の区別は平安中期のものを基準としているが、院政期はこれらが崩れてくる時期ととらえられる。