This yunomi is a gift from a sushi shop. In addition to the dragon motif, it bears the name and telephone number of the shop (not shown).
A yunomi (Japanese: 湯のみ) is a form of teacup, typically made from a ceramic material, being taller than wide, with a trimmed or turned foot. Unlike the more formal chawan tea bowl which is used during the Japanese tea ceremony, the yunomi is made for daily (or informal) tea drinking.
There are special pairs of yunomi called meoto yunomi (meoto means ‘married couple’). Meoto yunomi usually consist of two cups with the same pattern (sometimes in different colours) but different sizes and often slightly different shapes (the larger cup being the ‘husband’ and the smaller being the ‘wife’ cup).