Even so, the further western island is Attu in the Aleutians, but that has been shut down for decades. It's an emergency landing airport with little facility and prob no fuel. Nearest, that seems like "real" airport, is Adak or Unalaska. From there it's a pretty hefty jump to Japan, closer to 1500nm. A Jetprop could do it with the right winds, but only a few Avgas Commanders could deal with that hop without ferry tanks.
It's a challenging route.