At around 10 a.m. on September 24, 1192, he was born as the second son between the 1st Seii-taishogun of the Kamakura bakufu MINAMOTO no Yoritomo and his lawful wife Masako HOJO.
建久3年（1192年）8月9日巳の刻、鎌倉幕府初代征夷大将軍・源頼朝と正室・北条政子の間の二人目の男子として鎌倉で生まれる。