Although until the early Heian period, hitoe (unlined garment) was used as an undergarment, hitoe became larger and did not work as an undergarment because of the rise of Japanese original national customs and manners and accompanied change of costume during and after the middle of the Heian period.
平安時代初期までは下着として単衣が使われたが、中期以降の国風文化興隆に伴う服飾の変化により、単は巨大化して下着としての用を為さなくなった。