At that time, Emperor Tenchi who was trying to implement the ritsuryo system (a system of centralized government based on the ritsuryo code) also trying to introduce legitimate child succession (that is, Prince Otomo [Emperor Kobun] would inherit the imperial throne) instead of the old conventional succession between brothers-uterine so Prince Oama's dissatisfaction escalated for this.
当時、律令制の導入を目指していた天智天皇は旧来の同母兄弟間での皇位継承の慣例に代わって唐にならった嫡子相続制（すなわち大友皇子（弘文天皇）への継承）の導入を目指しており、大海人皇子の不満を高めていった。