About the "worst case" for Japan is "mutually assured destruction" of the two Pacific fleets. That's actually not too bad.
That occurs if the U.S. brings its bomber and fighter from the East coast, and uses its west coast fighter, battleship and transport in a counterattack on the Hawaiian Islands sea zone. The Japanese are likely to lose in all, one battleship, one carrier, one sub, and two fighters. The U.S. stands to lose one battleship, one sub, one transport, one carrier, and two or three fighters (in total), leaving the bomber and perhaps one fighter. That leaves a stand-off in the Pacific.
The U.S. may prefer this strategy if the Japanese player is better than the German player. But the U.S. loses at least a turn in the Atlantic by sending the bomber and fighters west.
Don Rae had a brilliant plan to defuse this threat: Move only the batttleship and sub into the Hawaiian sea zone, and leave the carrier in the Wake Island Sea zone, out of range of U.S. aircraft, while allowing two fighters to attack, and retreat to the carrier. You will lose the sub in the battle, and the battleship either in the battle itself, or in the counterattack. That's a total of 32 IPCs, versus 38 IPCs at stake for the Americans (possibly another 8 if they lose the transport from the Pacific in the counterattack.)
On the following Japanese turn, the lone U.S. battleship in the Hawaiian seazone is vulnerable to air attack from at least two fighters and a bomber, meaning that Japan stands to recover its "investment" of a battleship. And it still benefits from the setback to America's Atlantic buildup.