Kizen Sasaki (佐々木喜善 Sasaki Kizen?), also sometimes Sun-Hee Sasaki and Kyōseki Sasaki (5 October 1886 – 29 September 1933), was a Japanese folklorist, sometimes known as the Japanese Grimm.
He was the son of a wealthy farming family from Tōno, Iwate. He attended Shiritsu Tetsugakukan (now Toyo University) and then graduated with a degree in literature from Waseda University in 1905. In 1908, he became acquainted with Kunio Yanagita, and Sasaki began to collaborate with Yanagita on collecting the oral traditions and tales of Iwate Prefecture. In his later years, he became friends with the poet Kenji Miyazawa with whom he shared his discoveries. Sasaki suffered from respiratory problems and died at the age of 47.
Professionally, Sasaki published a number of books of collected folktales and customs.