ryūgū-zukuri 竜宮造

Lit. "dragon palace style." An uncommon double-storied gate. The lower story has a flat arched entrance whereby the same arched shapes ran through the passages from front to back. The white plastered exterior walls curve up and inward but have a surface on which the timber that supports the upper stories can be erected.
There are two well-known examples, built approximately 200 years apart. The earlier one dated 1653, is at Rinnōji Taiyūin Reibyō 輪王寺大猷院霊廟, Tochigi Prefecture and is called *Kōkamon 皇嘉門. 1 × 2 bays (2.22 m W × 1.82 m D). The measurements are based on placement and do not include the thickness of the plastered walls. The line of the lower story outer walls slope inward from the base about 30 degrees. The upper story is timber and very colorful with brilliant metal and lacquer ornamentation. The 2-stepped bracket complexes *futatesakigumi 二手先組 are spaced closely together but only across the front. The gable roof is covered with copper, dobanbuki 銅板葺, and simulates tiles *hongawarabuki 本瓦葺.
The second example is at Sōfukuji 崇福寺, Nagasaki Prefecture. The gate is dated 1849. It is 3 × 3 bays (11.21 m measuring the width from centers of outermost pillars and the depth from front pillars to rear pillars of the central bay. It has a 3-bay wide gate *sanmon 三門, with small gates attached on each side of the center one. Only the central bay has a second story. The three gates are covered with thick, white plaster and all entrances are of the flat, arched type. The small end bays have gabled roofs and are covered with tile. The outer end walls curve outward at the top. The central bay is large and high with rounded ends curving to form a flat surface for the second story. A flanking roof over the central area has no bracket complexes underneath. Above this rises an enclosure surrounded by a decorative balcony. The balcony, the windows and roof are decorated in a way that reflects a strong Chinese influence. There are single eaves *noki 軒, and the rafters are closely spaced *shigedaruki 繁垂木. The roof is hip and gable, *irimoya yane 入母屋屋根, and covered with tile. The carpenter's name is known to be one Ōgushi Goryōhei 大串五良平.
The ryūgū-zukuri is often said to be a type of *hakamagoshi 袴腰 because of the curving of the outer walls.