Well, maybe three solitudes: Japanese staff, foreign staff and kikokushijo (帰国子女) staff, who have the toughest row to hoe. It gets even more complicated when you get into other castes: halfu, and Japanese staff (usually female) married to foreigners. It's not important to consider the foreign staff married to Japanese (usually foreign men to Japanese women), because the foreign and local staff don't exclude them: that's a Japanese specialty kept for their own...
These places are all the same. There is an office where the financial work and the quartermastering goes on. Then there is the foreign teachers' administrators, also foreign, to whom the teachers answer. There is not a lot of communication between the two, on the clock or after. Do not imagine this is because of language barrier: most of the Japanese staff speaks decent or better English, and some of the foreign staff speaks middling or better Japanese.
What foreign staff do not realize from the beginning is that the Japanese work longer hours, though not efficiently; and that many Japanese staff resent our shorter hours, no matter how busily pursued. It goes a long way to throw around: 'otsukaresama-desu'. Foreign staff also do not realize that they will never date the Japanese staff, because the latter are too smart to get themselves ostracized for doing so. Never mind that better than half of the young Japanese women on staff have, or have had several, foreign lovers - how do you think they learned conversational English? - they are too wise to 'shit where they eat'.
The kikokushijo (帰国子女)? If 'halfu' they are counted as foreign staff by the locals (how nice). If Japanese... they put the Japanese off of their ease, since they do not quite know which hole to put that peg in. The Japanese like nothing less than not having a concrete answer to a social situation. On the other hand, we 'Westerners' have our issues: some assume that the foreign educated are 'westernized', and subconsciously assume that this is a good thing. Well, ours is a proselyting culture.