One thing I don't get - isn't their timeline a 'better' one?

[deleted]

How about a fact that Koreans of the new timeline lived pretty much under dictatorship?
Nowadays too South Korea and Japan are pretty much equal economically... Though, of course, if we take into account North Korea it's different.
In the other timeline Berlin was bombed using nuclear weapons......

It looked ok on the first glance but when you looked deeper you saw that Japanese occupied all the best jobs and Koreans were second class citizens (except some, like the main hero)

And no, I'm not a Korean...

No. The corrupted timeline is NOT a BETTER timeline.

As a Brit, it might be more understandable film where instead of Japan, it was Nazi Germany. And all the Aryans and collaborators had prosperous lives and was a "better world". But it would be a false paradise build upon the suffering of subjugation of those excluded from the ruling power.

Although there was no bombing of Hiroshima and Nagasaki, there was instead the atom bombing of Berlin.

Also, if you noticed, it is mentioned that most of the people in prison are Koreans. And the small Koreatowns that still exists are considered slums and shady places. And from the continual mention of the main character's Korean heritage, despite all his contributions to the Japanese government and his work, he is still considered an outsider, distrusted, and not fully accepted.

In other words, this corrupted timeline is "better" and "prosperous" for only or mostly Japanese people. Most of the people subjugated by Japan then, (most of Asia) would have been considered second class citizens, with limited autonomy or freedoms.

And if you have EVER researched ANYTHING about Japanese Imperialism, then you would DEFINITELY know that they are not the good guys.