When Crown Prince Atsuakira requested to withdraw from the crown princeship during the reign of Emperor Goichijo, the title of imperial prince was specially granted to the crown prince's son (grandson of Emperor Sanjo), lifting the strict measures regarding entitlement and allowing Koshin two generations and beyond to be able to receive the rights granted to imperial princes by becoming the adopted child of an emperor.
後一条天皇の時、皇太子敦明親王が皇太子辞退を申し出ると、親王の男子（三条天皇の孫）に特に親王の称号を許して以後厳密な規定がされなくなり、孫以下の皇親でも天皇の養子縁組・猶子となって親王の待遇を受ける事が可能となった。