Circle, Triangle, Square by Sengai consists of three bold ink forms—a square, a triangle, and a circle—rendered on paper in the early 19th century. The three shapes are arranged horizontally, each drawn with a single, confident brushstroke. Black ink is used throughout, and the forms stand out starkly against the pale, textured background.

To the left of the shapes, there is a column of Japanese calligraphy and a red seal stamp. This work is an example of Zen painting from Japan. Paintings such as this often employed simple geometric forms and calligraphy to express philosophical ideas within the context of Zen Buddhism. Sengai was a Rinzai Zen monk known for using art as a teaching tool, and this composition reflects the meditative and direct character typical of Zen ink painting from the period.