So are these only encountered on the Vampire routes then? The last bit in regards to Mila seems to imply that they are only encountered on her Vampire routes.
Hopefully i'm wrong since i'd absolutely LOVE some delectable yurilicious h-scenes with them and Mila after all... <3 <3 If there's no additional slime girl Mila content to be had then having some yurilicious lovin' is a good enough substitute imho. ^-^
Also, hearing about ship decks is reminding me of the fifth mission bgm of Metal Slug 4, which also happens to takes place on a ship with pirates as well.