The Kouka Teahouse at the Former Residence of Prince Asaka was designed by Sason (Zesokuan) Nakagawa (1880–1957), a tea master from the Mushakojisenke school of Japanese tea ceremony. It was constructed by Masaya Hirata (1900–1980), a master sukiya carpenter from Osaka, and completed in 1936. The name “Kouka,” which is a combination of two Chinese characters meaning “light” and “splendid” to give a meaning of “resplendence,” is said to have been bestowed by Prince Yasuhiko Asaka himself, and the plaque with the tearoom’s name on it is written in the prince’s own hand.

The teahouse consists of three tearooms: the koma, or small room; the hiroma, or large room; and the ryureiseki, or room with chairs. The main roof is laid with sangawarabuki roof tiles, which are S-shaped pantiles, while the eaves are covered in kokerabuki wooden shingles wrapped in sheets of copper. The ryureiseki is a style of tearoom devised by members of the Urasenke school of Japanese tea ceremony in the early Meiji period to cater to guests from overseas who were unaccustomed to sitting on tatami floors. This style of tearoom would go on to become popular within various schools of tea ceremony after World War II, but its inclusion in a pre-war teahouse like Kouka is something of a rarity. The teahouse is notable for its high ceilings and bright, spacious interior throughout the structure, which reflects the prince’s tastes and harmonizes well with the Art Deco style of the Main Building.

In 2015, the teahouse was designated an Important Cultural Property of Japan along with the Main Building and other structures, and was reinforced in 2016 to withstand earthquakes.