When I took over the running of a bookshop in Cornwall in 1988 I inherited a customer who had been incarcerated in the notorious Changi prison camp and had become one of four prisoners who not only survived the experience but had smuggled out drawings, knowing that if caught they'd have been executed. One of them was Ronald Searle, the creator of St. Trinian's. When one day a Japanese woman came into the shop while he was sitting there (he was considerably disabled) he could not have been more charming to her, never giving a hint as to his experiences. I thought it showed great tolerance and forgiveness on his part, but he was such an admirable, uncomplaining man who'd seen the worst of humanity but hadn't allowed it to destroy his spirit, only his body.
Though to be honest said lady may well not even have been born by 1945.
Humans can be strange; and often far from rational.
@Busaholic's acquaintance was, it would seem, indeed a forgiving, and beyond-decent, person -- maybe to the point that he would have acted with kindness toward someone Japanese whom he knew to have committed World War II atrocities -- logic as to who "could have", and who manifestly "couldn't have", playing no part. I remember reading about a Dutch guy who had been, at a very young age, interned by the Japanese as an enemy citizen, in what is now Indonesia, in World War II -- his experiences had been terrible, and he had atavistically loathed everyone and everything Japanese ever since. Long post-war: the firm for which he worked in a fairly high management position, sometimes entertained in the course of business, Japanese representatives of undertakings in that country. The Dutch gentleman concerned, found -- consequent on his wartime experiences -- any potential contact with anybody Japanese, intolerable. His employers understood his situation, and "spared" him accordingly. The guy experienced strong regret and remorse over this -- he "knew with his head" that any Japanese visitors-on-business would have been born well after the war, so not guilty of any horrific deeds therein; but what he "felt with his gut" was stronger, and for him unsuppressable. One would reckon -- individuals and their reactions, greatly differ.
This thread strikes a chord with me, by reason of a recent visit of mine to relatives. They're a couple -- a few years older than me (they both born 1943, me 1948) -- he's the "blood relation" to me. In conversation with his wife, "things German" came up by chance -- initially, about nothing historical. It emerged that to a large extent she is still, as it were -- after more than three-quarters of a century -- fighting World War II (at whose very end she was at most, twenty months old
). She went into quite a diatribe of hatred against Germans and anything-and-everything German; a conversational interlude, and then she went, unprompted, on to Japan -- even stronger hate, because of Japanese doings against Allied folk in that war -- I felt an implication that Hiroshima and Nagasaki were not one-hundredth of what that filth truly deserved.
After the German-related rant, I asked her whether these feelings on her part would extend to any individual Germans whom she might encounter. She acknowledged that she had been acquainted with a German girl, whom she found very nice and likeable. This lady, my relation-by-marriage, is in fact in many ways a lovely person -- individual quirks, and people are often weird -- lady concerned, is rather an attention-seeker: tends "in leisure hours" to spout extreme and belligerent stuff, but is in real-life matters extremely kind and caring, in deed as well as word. There strikes me as another widespread oddity of the human race: that with nations or groups other than one's own, which are widely disliked / despised / feared / shunned by one's own bunch (including by oneself) -- this sentiment is rather in the abstract; with individual members of the disliked / despised - etc. crowd whom one happens to encounter: it's more than likely that one will rate them as likeable and "surprisingly human" (while regarding them as exceptions). Admittedly there are some extreme situations, e.g "WWII, us, and Japan", which can weigh against that tendency.