Chogetsu (1714-June 15, 1798) was a mid-Edo period monk and poet. His secular surname was Nishiyama. After he took the tonsure and became a monk, he took the name Chidatsu. He also went by four other names, Suiunken, Suimuan, Fushinken, and Yua. He was born in Tamashima, of Bicchu Province. He is counted as one of the Four Heavenly Kings of Heian waka (poems).
He came to the capital at the age of thirteen, and initially ascended Mt. Hiei and began learning Tendai sect teachings, but later changed his sect to the Jodo (Pure Land) school. He studied waka poetry with Saneoka MUSHANOKOJI, and thoroughly mastered the esoteric secrets of the Nijo family. A personal anthology of his poetry exists, called the 'Suiun wakashu' (Collected Waka of Suiunken).
His posthumous Buddhist title was Saint Byakurensha Setsuyo Yua.