It is a Oni-Hagi Hiissen Chawan. Hiissen is Japanese and is a meaning referred to as "Washing a brush."
Since form resembles the container from which a brush is washed, it came to be refered to as Hiissen Chawan. The Hagi ware clay with which three kinds of grounds were mixed is used for the clay of this work (Daido, Mishima, Mitake). The clay which blended rough sand is called Oni-Hagi. The glaze currently used for this work is straw-ashes glaze, and is the original blend glaze.