The theory claimed by Yonekura and Kuroda has wide-ranging evidence, for example, the form of the headdress worn in the portraits is observed only after the end of the Kamakura period, the hair pin type sword has a form that was established from the 13th to the 14th century, the silk in such a size used for the three portraits appeared after the late Kamakura period and silk was connected before that period, and the style of expression (drawing of eye brows, eyes, ears, and lips) of the three portraits is strongly similar to the one in the middle of the 14th century; based on such evidence, it is natural to suppose these three portraits were drawn in the period of the Northern and Southern Courts.
米倉・黒田らの論拠は多岐に渡るが、主要なものとしては、着用している冠の形式が鎌倉末期以降にしか見られないこと、毛抜型太刀の形式が13世紀-14世紀のものと考えられること、三像に使用されるほどの大きさの絹は鎌倉後期以降に出現し、それ以前は絹をつないでいたこと、三像の表現様式（眉・目・耳・唇などの画法）は、14世紀中期の肖像との強い類似が認められること、などであり、これらから三像の成立は南北朝期に置くことが最も自然であるとする。