Meh, I just made my own and stuck it into the box with the counters and such.

Actually, it varies- against Germany, it’s completely unnecessary; however, if Germany is defeated, then it’s necessary to have a navy to fight Japan. Of course, by this point, Japan is probably screwed anyway.

Japan or Russia.

Japan tends to be underestimated, and can easily expand across Europe if it’s lucky.

Russia is right in the middle of the action, and it tends to have some really big battles.