My dad was in a Jap concentration camp with my grandmother, grandfather and uncle in the interior of China because they were Belgian living in China when the Japanese invaded. He was there three years. Starving. Saw people beaten to death as a ten year old kid.
A friend of my parents was in the marines. He was part of the marine detail at the US embassy in Hong Kong. He should have had diplomatic immunity but signatures were lacking on documents necessary to prove it. He was in various Japanese POW camps from December 8, 1941 to the end of the war.
I am sure his stories and your dad’s are quite similar.