Although there were times when some retired emperors existed, only one person was called Chiten, there was even an incidents of fighting between a retired emperor and the emperor to take the position of Chiten (the Hogen War).
複数の上皇が併存することもあったが、治天となりうるのは1人のみであり、治天の地位を巡って上皇・天皇同士の闘争さえ発生した（保元の乱）。