The Walls are Closing in

In the skies above Japan, the Luftwaffe reigned supreme. By now the entire Japanese Air Force had been reduced to rubble, the factories that produced the Japanese aircraft destroyed, and the supply lines to facilitate their manufacture nonexistent. 

The only thing that could possibly harm German pilots was what little remained of the anti-aircraft weaponry which was sparsely spread across the Japanese Mainland. However, with each shell fired, there would be no replacement. Not to mention that German bombers were capable of flying at such heights that the Japanese flak guns were incapable of hitting them.