The story in Nenokuni is a form of mythology called kadaikon (subject marriage), in which a person is subjected to hardship by a marriage partner's father but eventually overcomes it with the advice or help of a marriage partner.
根の国での説話は、結婚相手の父から試練を与えられて、結婚相手の助言や手助けによって克服するという課題婚と呼ばれる神話の形式である。