Because there are no explanations about atsu-yo (thick torinoko-colored paper) in both dictionaries, it seems that the atsu-yo of ganpishi had been called torinoko since the Heian period.
両集ともに厚様の説明が欠けていることから、平安時代から和紙（がんぴし）の厚様を鳥の子と呼んでいたと考えられる。