Reigen was the 16th son of Emperor Go-Mizunoo. His mother was the daughter of the Lord Keeper of the Privy Seal Sono Kion (?, 内大臣園基音), Lady in Waiting Kuniko (?, 国子).
Name
His posthumous name was created during the Meiji Era by combining the kanji from the names of two previous Emperors, Kōrei (孝霊, 290-215 BC) and Kōgen (孝元, 214-158 BC).
Life
1654 - Becomes heir upon the death of his eldest brother, Emperor Go-Kōmyō
1663 - Ascends the throne upon the abdication of his elder brother, Emperor Go-Sai
1687 - Begins to rule as a cloistered emperor, abdicating in favor of Imperial Prince Asahito ( Emperor Higashiyama)
1713 - Enters a monastary under the name Sojō (?, 素浄)