Not quite true… if Japan is building DEFENSIVELY, then yes they can.
Japan can get 11 points on Naval defense with a single AC build and land based FIGs, FIGs that can still be used in Bury, China or even India depending on the location of your AC’s.
From then on out, Japan can get 11 more points of defense for 36 IPC’s. Spread over 2 rounds, that still allows about $25 IPC to be sent to Asia, with the TRNs to support Asia adding to your defensive fleet.
To get 11 points on attack with navy, you need to spend a LOT more than $36.
2 BB and 1 DST is 11 points and costs $60
6 SUBS gets you 12 points and costs $48, but must be protected with surface ships or they are sunk by Carrier based FIGs before they even get to attack.
4 DSTs costs $48 for 12 points of attack
And with AC’s and FIGs, you have to spend $62 for 2 AC’s and 3 FIGs.
Against that kind of IPC outlay, it will take many turns for the US to be able to punch through a consolidated Japan navy… turns which are used to reduce US income in China and Sinkiang, and start making more IPC’s in India, Bury, etc.
Meanwhile, Germany has only 2 opponents, and for 3-4 turns they can keep the UK navy at bay with startig navy, an AC and their air power… that leaves Russia outspent 2-1… gates of Moscow before UK even has the ability to land forces…