Karesansui landscape, master sketch model

Quick answer：

Karesansui, also known as Zen garden, is a traditional Japanese rock garden that represents a natural landscape in miniature, often using rock, sand, and moss. The 'master sketch model' likely refers to a detailed and scaled-down representation of such a garden, created by an expert sketch artist. This type of model is often used for planning, design, and artistic expression in landscape architecture.