This was because on his death bed in 1272, Go-Saga had insisted that his sons adopt a plan in which future emperors from the two fraternal lines would ascend the throne in alternating succession.
Ini karena di ranjang kematiannya pada tahun 1272, Go-Saga telah bersikeras bahwa anak-anaknya mengadopsi rencana di mana kaisar masa depan dari dua garis persaudaraan akan naik takhta secara bergantian.