Diameter 10cm, high 5cm
I'm afraid this is a fake. Tea cups of this type are not my specialty, but I have seen and handled a couple.
Hare's fur bowls/cups do have a brown top rim, not a yellow one, and the glaze should not have gloss. In addition, the clay tends to be darker and lower glaze rim often is uneven and has drops in the glaze.
Upon enlarging the rim it looks as if the top rim is covered with gilt. Is it?
Hare's fur bowls don't look that way. There are two glaze applications done separately, what remains is a brown top rim easily 1-2cm wide, not always. This was not done this way.
I would avoid this type of Tenmoku bowl or first buy one from a shipwreck to compare. There are too many fakes out there.