Während des Zweiten Weltkriegs erklärte Polen Japan den Krieg. Japan lehnte dies ab und lehnte die Kriegserklärung einfach ab

Yep. Poland and Japan were sharing intelligence about the Soviets. The Polish were also seen as being honourable and part of the Bushido code.

Perhaps because Poland had no territory to war against?

Pilsudski offered to raise a Polish legion to fight alongside the Japanese during the Russo Japan war. They politely said no but financed a lot of shared collaboration

Poland’s government was in London at the time, so it is unclear whether they acted under some kind of pressure. Sikorsky Museum archives, London, might have an answer.

Pov: random small chiefsdom next to you in aoh3