Sosei

Sosei (Japanese: 素性 or 素性法師, c. 844 – 910) was a Japanese waka poet and Buddhist priest. He is listed as one of the Thirty-six Poetry Immortals, and one of his poems was included in the famous anthology Hyakunin Isshu. His father Henjō was also a waka poet and monk.
Sosei entered religious life sometime after his father, who took the tonsure after the death of Emperor Ninmyō in 850.