I have come across this 'embassy church' in Japan and don't quite know what to make of it. How common is it to establish these kind of churches and what do they mean? Is 'embassy church' even an accurate translation of the Greek or Russian terms?
I'd be grateful for any help.
I'm not quite sure that Russian 'подворье' means 'embassy church'. There was a lot of different 'подворье' for merchants from different countries. This is more like hotel for people unified by some parameter (country, religion, kind of trade). However, this term was used more frequently as a church term (and in modern Russian it used in church or monastery context only).
Wikipedia describes this term pretty good.
https://ru.wikipedia.org/wiki/%D0%9F%D0%BE%D0%B4%D0%B2%D0%BE%D1%80%D1%8C%D0%B5
There are many established faith fellowships in Norway under the supervision of a foreign spritual authority, most of them renting space in local churches. One example in my home town (Trondheim) is the Mekane Yesus Church (Ethiopian). This might be understood as an "embassy church" in one sense. You may be aware of the other meaning of metochion, that of an established fellowship as an extension of a monastery. F. ex. on the island of Lesbos, the main monastery of Limonos has for a long time had many such extensions. One of them, built in the 16th century, has been restored and is today used by permission from the monastery as a study center by Agder University.
ambassy church -- it's a rendering of the Russian expression посольская церковь, that is, a church built for the ambassade's staff but (normally) open to everybody.
This is not the same as μετόχιον / подворье (a sort of ecclesiastical ambassade of a monastery or some local Church).
Thanks for this, everyone. If you don't mind, I have a further question:
Is it possible that this church in Japan is an embassy church both in the sense that Edward and Sturla are talking about and also in the sense that Basil means?
And what kind of canonical status would it have? If it's called, in Russian, Подворье Русской Православной Церкви Московского Патриархата в Японии does this mean it's a part of the Russian Orthodox Church rather than the Japanese Orthodox Church (which is autonomous under Moscow)?
Подворье Русской Православной Церкви Московского Патриархата в Японии -- this means μετόχιον (which is not an embassy church sensu stricto). This is a church where the rector is a clergyman of the Patr. of Moscow who is subordinated directly to the Patriarch of Moscow and is his representative in Japan. He is not a member of the Japanese Orth. Church.
Such μετόχια became common under the Ottoman rule, when, eg., the metochion of the Ecumenical Patriarchate in Yassy (within a metropolia subordinated to C/ple) was an important Church centre.
PS. As far as I know, the embassy church in Japan also exists, it is under the patriarch, too, but not подворье. Its rector is not a representative of the patriarch.