I'm guessing that the clothes came off a Yotsuba doll standing to the top right. The image source does state Yotsuba twice in the URL. Looking at the source site however: http://anigimi.hp.infoseek.co.jp/pm_yotsuba/yotsuba3.html It appears to actually be the clothes of Yotsuba from Sister Princess however, it was probably caught up in error in a mass tag edit.