'Kami-gate'. A gate, often an impressive roofed construction built in the style of the shrine, which allows the approaching visitor to pass through the shrine's encircling walls or fences (tamagaki) and can be closed at night. There are several types or designations of shin-mon. Ro-mon can be applied to any category but sometimes refers to a gate formerly reserved for the imperial messenger to the shrine. So-mon usually means the gate through the second tamagaki but may also mean outer gates. The names yotsu-ashi-mon 'four-legged gate' and yatsu-ashi-mon 'eight-legged gate' indicate the number of pillars supporting the central pillars from which these types of gate are hung. Kara-mon means a gate of multi-gabled Chinese (Tang) style from the Kamakura period and zuijin-mon is a gate which either enshrines the shrine's guardians (zuijin='attendant') or is flanked by their statues. The guardians used often to be Buddhist figures, and many were destroyed in the wake of the shinbutsu bunri decrees of 1868. Shrine gates were a continental, Buddhist-influenced development of primitive shrine architecture. Especially with the spread of ryobu shinto it became common to build two-storey portals instead of simple torii. Examples of classic Buddhist-style gates are the Yomei-mon at the Nikko Toshogu and the gates of the Gion, Kamo and Hakozaki shrines. Gates such as those at the Meiji and Yasukuni shrines constructed since the separation of Buddhas and kami in 1868 are largely of unpainted wood with a thatched, tiled or copper roof in a nineteenth century 'pure Shinto' style, though the Sugo-isobe jinja in Ishikawa has a gate built in 1875 in stone and ironwork in a unique three-storied semi-European fashion.
A Popular Dictionary of Shinto. Brian Bocking.