A guy on Reddit said it best. Bismarck wont be added, until after Washington gets added to the JP server. So never.
Only reason JP has yet to get that event is because of the big shuffle to sync up events and it's much too big to just stick in some stray gap.
If the wiki page is anything to go by, Bismarck is the only LEGENDARY ship in the game. Also one shouldn't want to be in too much of a hurry to get ships lest a KC situation occurs (Where they have to resort to DEs/etc because they blew through the bulk of japanese ships stupidly fast)