This is a zodiac sake cup (guinomi) from Tokoname, known for its earthy texture and the distinctive bluish-gray glaze of Mikio Osako. It's from the Year of the Rooster, 1993. The diameter is about 8cm, and it's a bit flat, so it could also be called a cup (sakazuki). The second photo shows the character for "Rooster" (酉). I bought it because I was born in the Year of the Rooster. The fourth photo shows the potter's mark. It will be sent with the original box, yellow cloth, and brief biography that came with the purchase.