Board Thread:Questions and Answers/@comment-24731329-20150303101022/@comment-460323-20150303122925

Do note that you still have to complete the subs chain quest to unlock Bismarck construction.

I suggest spamming 1-5 first 3 nodes with CL/DD once your HQ lvl hit 40. You'll need to Kai Ni a few good DD/CL, particularly Kitakami/Ooi, for later maps and events. Think of the power-leveling as side objectives while you grind for subs~