Since you don’t plan to leave the airport, Japan, Hong Kong and Korea in that order. I had been on all those places before retiring from the military. Japan’s Narita international airport is very nice. You’ll find great food to eat while waiting for your next plane. So does Hong Kong and Korea. However, the Japanese are the nicest people I’ve met in my navy career.
Good luck and be safe. It’s been a long time since I’d been in Manila.