Not many people understand the situation in Japan, so allow me to elucidate;
Japan post WWII was not allowed to operate a proper military that could project power beyond its own borders and close interests like Okinawa. They've had 'Self-Defense Forces' that accomplish this mission and host U.S bases which house U.S forces capable of projecting the power they'd need to remain a player internationally. Over the last few decades though, Japan has been slowly lifting its own restrictions and building up its military, especially its navy, into a dynamic and capable arm capable of projecting power across the Pacific, a capability it really can't technically have.
This has especially aggravated the Chinese and Koreans, who have stepped up their own naval programs, and in return Japan continues to build up its own capabilities with the support of countries like Australia and the U.S. The logic in our camp is essentially, "OK, we whipped Japan so badly that they've been down for three quarters of a century, it's time to let them do as they will."
The joke of the meme is that Japan currently operates a navy far in excess of what it is technically allowed to have. A coastal-defense force is NOT a blue water navy. They're not really comparable, honestly. Japan has the latter, not the former, hence why this meme is indeed funny.