Um, no. Russia and France are the easier marks since France is massively under equiped in the Pacific and the Russian Navy effectively doesn't exist anymore. Plus Russia is the one power the Japanese have an actual grudge against. Also, French Indochina is much more profitable, and industrially useful than Micronesia (because Rubber.)
Plus, there's the whole issue of the IJA being very close to their german counterparts.
If they were to enter the war separate from Britain, and weren't going to just sit by and profiteer off war loans, the choice is really obvious.
It's like the Ottomans not taking the chance to repudiate 70-100% of their outstanding debt from the Crimean war (which was so burdensome as to dictate internal financial policy to an absurd degree.)