This is a purple Shino guinomi (sake cup) by Kazu Yamada. Purchased at a solo exhibition at Ginza Kuroda Tōen, it has been used a few times and then stored at home. I believe it is a well-fired piece. The size is approximately 5.5 cm in height and 6.5-7 cm in diameter, making it an easy-to-use size. Kazu Yamada's uncle is the Living National Treasure, the third generation of Jozan Yamada. He studied under the late Karato Kuro.