Despite Emperor Keitai already had several wives and a lot of children before he moved to Yamato, he took the older (younger) sister of late Emperor as his Empress.
継体天皇は大和に入る以前、現地で複数の妃を持ち沢山の子がいたが、即位後先代天皇の姉(妹)を皇后をとして迎え入れた。