well gameplay wise you can find ships as you battle through the maps/waters but how you get them is... well never explained however it just happens as well that Naka is one of the more common "drops" so theres probably a joke to this, and if your ship daughters get sunk they turn into the abysmal fleet enemies such is the fate of these ship daughters
Hope there won’t be a certain creature call Incubator...
Fuuu, aye aye.OOOOOK♪Admiraaaal, we've captured an enemy supply ship.I'll take it from here so please enjoy yourselves in the dock.A Destroyer's Destiny 16To a living soul... I got it.Ooh, Good job.To be continued...before it was too late......You probably know this already, but don't breathe a word of this...Imperial Navy
Yokosuka Naval Dock...But it's a good thing that we rescued her... ...Originally this would have been something that every fleet girl knew about...