Raku ware (楽焼 raku-yaki) is a type of Japanese pottery traditionally used in Japanese tea ceremonies, most often in the form of chawan tea bowls. It is traditionally characterised by being hand-shaped rather than thrown; fairly porous vessels, which result from low firing temperatures; lead glazes; and the removal of pieces from the kiln while still glowing hot. In the traditional Japanese process, the fired raku piece is removed from the hot kiln and is allowed to cool in the open air. The familiar technique of placing the ware in a container filled with combustible material is not a traditional Raku practice. (Wikipedia)
Here: a bowl by Hon'ami Koetsu (1558-1637), a noted designer-connoisseur who played a prominent role in Kyoto artistic circles during the late sixteenth and early seventeenth centuries.