Just a few days after his twins' birth, Undyne attacked the Yukan Family village with the other members of the royal guard, setting it ablaze & killing most of the Yukan Family due to Card being a hybrid child and wanted to kill him for the good of the monster race. Yūkan'na followed his wife's orders, taking their children and running away. As he ran, he realize there was only one way to save his children's' lives. He hid them in an ally then after a tearful goodbye he ran, leading the guards away from them.

( Undyne belongs to Toby Fox )