The Kohiki (slip-coated) chawan (matcha bowl) is made from dark, iron-rich clay glazed in pale liquified clay called a white slip. Each wheel-thrown bowl reveals the natural warmth and rustic variations characteristic of traditional kohiki pottery. The base is finished with a takenofushi koudai (bamboo-node foot ring), and the rim is shaped with a mutual spout, making it ideal for whisking and pouring matcha.

Sugawara Kengo founded Yōki Kiln near Mount Katsuragi where the Shugendo fire ritual began, which is yet believed to transform the world's corruption into goodness. He applies the Shugendo ritual to his own ritual of transforming the earth's clay into a peaceful tea experience using his wood-fired kiln.

Handmade Japanese tea wares are referred to as Kogei in Japan; the concept that beauty resides in the artisan’s work through nuances, wabi-sabi (irregularities), and defining differences between each piece.