Japan can build an IC on any of its original territories. Since Japan begins the game possessing much of North East China, it may build minor ICs on those territories which have a value of 2.
I think if Denmark is neutral then the straights should be open to any country. Germany should take Denmark to keep the UK fleet from entering….I will add this in my 6.1 rules coming out this weekend.
He saw the planes. He knew the risk. It’s not like you were hiding anything or doing anything sneaky. If he was 100% sure what the pieces were he should have doubled checked before calling done to his turn. No do overs. I normally don’t allow do overs on phases of a turn let alone whole turn. Once you say That’s all the combat moves no going back during Non-com and finding a combat you missed.