By skyforbes Spring Air Japan, flight IJ005 flying Narita, Japan to Shanghai on Dec 1.
A man boarded and demanded another passenger swap seats so he could sit next to his girlfriend. The other passenger refused, the flight attendant told him to take his assigned seat.
For the next two hours he continued to complain to the flight crew over how unfair this was. He was so incessant with his poor behavior that after about 2 hours, with about 30 minutes until landing the pilots decided to return to Narita to have the passenger removed in his home country.
The other passengers were given 10,000 yen for the inconvenience.