Also written 突揚窓. A skylight built into the sloping ceiling *kakekomi tenjō 掛込天井 of a tea ceremony room *chashitsu 茶室 to provide both light and ventilation. It is not positioned between the bamboo rafters, but instead is placed so that one rafter passes across the center of the opening. A wooden frame is built into the roof along with a hinged cover. Traditionally, oiled-paper covered a light frame, abura shōji 油障子 (*amashōji 雨障子), on the inside. When the window is opened, the oiled-paper shōji slides up, and the bottom edge of the hinged cover is pushed up with a pole. Nowadays, glass is used instead of oiled-paper.
The exterior appearance and structural methods differ according to the type of roofing used. Preventing leaks is the most difficult problem. Therefore, the hinged wooden cover must fit perfectly to forestall any accumulation of rainwater seeping in along the edges.
Skylights are placed on the sloping roof above the host's mat *temae datami 点前畳, above the guest's mat *kyaku datami 客畳, sometimes above the hard-packed earthen floor *doma 土間, and on the interior side of a pent roof with a long eave nokibisashi軒廂. Some tea ceremony houses have two skylights.
Example: Jo'an Uraku'en 如庵有楽苑 in Aichi Prefecture; Katsura Rikyū Shōkintei 桂離宮松琴亭; Daitokuji Gyokurin'in Kasumidoko-no-seki 大徳寺玉林院霞床の席; Daitokuji Shinju'an Teigyokuken 大徳寺真珠庵庭玉軒, also in Kyoto.
Jo'an Uraku'en 如庵有楽苑 (Aichi)