Kogosho

The Kogosho is a palace that began to be built in the Imperial Court from the medieval period. It features a central area with three tatami-matted rooms arranged in the Jodan-no-ma (Upper-Floor-Level Room),the Chudan-no-ma (Middle-Floor-Level Room)　, and the Gedan-no-ma (Lower-Floor-Level Room). By the Edo period, it had evolved into a unique palace architectural style with Hisashi（a wooden-floored space) attached on all four sides.
The layout of the Kogosho, featuring upper, middle, and lower floor-level rooms, was designed to accommodate Imperial audiences with samurai and envoys from the shogunate. It is best known for the “Kogosho Conference,” held during the Meiji Restoration to discuss the treatment of Tokugawa Yoshinobu following the Taisei Hōkan (the formal return of political authority to the Emperor).
The Kogosho has occasionally served as a substitute for Heian-period palace buildings with historical significance, particularly during important imperial ceremonies. Alongside the Shishinden and Seiryōden, it has been the site of key rituals related to imperial succession.
Reflecting its ceremonial role, the Kogosho features architectural elements similar to those of the Seiryōden, including fusuma shōji (sliding doors decorated with Konjobiki multicolored designs), nuno shōji (fabric-covered sliding doors with ink paintings), and shitomi-do (latticed shutters). When the tatami mats and partitions are removed and traditional furnishings are arranged, the space can be transformed to resemble a Heian-period palace interior.
Due to its high practicality, the Kogosho was also used for various purposes, such as waka poetry gatherings and musical performances.