The built-in table and staggered shelves in the northern part of the study are what remains of the oldest ornamental objects of the era and are extremely valuable to Japan as the source of the Shoinzukuri architectural style and the thatched tearoom.
書斎の北側に設けられた付書院と違棚は現存最古の座敷飾りの遺構であり、書院造や草庵茶室の源流として、日本建築史上貴重な遺構である。