Vintage OMC Kozangama stacking bowls

Stackage bowls / trinket boxes. Circa 1970s. In great condition with slight signs of wear on the bottoms. One bowl has some subtle marks on the rim (as pictured). OMC (Otagiri) is a distribution company which has brought so many beautiful Japanese pieces to the US. This was made by Kozangama 庫山窯 which is located in Gifu Prefecture in Japan. The style is minoyaki.