Height: 8.3 cm; Mouth diameter: 10.3 × 11.5 cm; Foot diameter: 5.0 cm
This tea bowl features a gently rounded square body from the rim to the mid-section and is formed with a thin wall throughout. It is believed to be modeled after Ryōnyū’s own gently rounded square-shaped tea bowls. The foot is carved into a flat, single-walled foot with a flattened base, and the hollowed-out area inside the foot is nearly circular. The glaze applied, leaving the foot and its sides exposed, is rich in variation: from the inside toward the rim, it lies thick and smooth like a curtain glaze, while on the outside it is applied thinly, with some areas showing yellow peeling. A vermilion glaze flows vividly from the inside toward the rim. From the middle of the bowl to the edge of the foot, Ryōnyū’s characteristic irregular glaze breaks run around the rim, exposing the white clay of the foot. A hidden seal is stamped inside the foot and on the middle of the bowl. On the underside of the lid, Ryōnyū himself wrote, “Black Square Tea Bowl, Midwinter of the Year of the Rat, Made by Ryōnyū (signature),” suggesting that this tea bowl was created in the 11th year of the Bunsei era, when he was 73 years old.
