trying to do some research, behind this gate,... would there be a shrine? (what religion?) or is this just a decorative gate that can be used in front of any residence?
It's a Shinto gate. This page, among others, says:
"Torii
A distinctive arch or gateway erected at the entrance to the sacred precincts of a shrine, separating the inner area from the profane world surrounding it. May also be erected along the avenue of approach."
(no subject)
Date: 2004-06-14 04:24 pm (UTC)"Torii
A distinctive arch or gateway erected at the entrance to the sacred precincts of a shrine, separating the inner area from the profane world surrounding it. May also be erected along the avenue of approach."