A 20th century Japanese Agano pottery oil tsubo or vase of that form. The compressed spherical form with vitreous green glaze and blue pooling from the rim on high, waisted neck trending to a blue iridescence dripping where meets a thin, clear matte glazed buff body around the girth. The bottom unglazed around the flattened foot with single incised character off center - looks like it reads "Sei". Good condition - some bubbles in the glaze popped in the kiln. Diameter about 7 1/4 inches (18.4 cm). Height about 4 1/4 inches (10.8 cm).