reverse culture shock
The disorientation felt when returning to one's home culture after living abroad, as familiar things now seem foreign.
After returning from studying abroad, I felt unsettled for a while due to reverse culture shock.
Reverse culture shock can be felt more strongly by those who have lived abroad for a long time.
Compound of 逆 (reverse) and カルチャーショック (culture shock), a direct loan translation of English 'reverse culture shock'.