Upvote:1
I think you could avoid checking-in baggage to Warsaw (which you won't be able to reclaim without entering), and check-in online for the second leg of your trip and just transit airside.
However, there's a fat chance that you won't be allowed to board plane in Kiev, since you're not allowed to enter destination country.
Why don't you renew your passport using Japanese embassy consular services? They should do exactly that.