What an interesting story; I have never heard this before.
I don't put much stock in Wikipedia but based on the dates, it appears that he had been in China before the Nazis took power in Germany; he may have joined the Nazi party simply for professional (and not, ideological) reasons.
I came across John Rabe‘s story by accident. As I see it, his heroic efforts are on the same level as those of the more-famous Oskar Schindler.
And like Schindler, Rabe died in poverty.
As the old saying goes, no good deed goes unpunished.
In this life, anyway.