So... does the kraken show up while fighting the obligatory "ghost pie-rat" or does MC summon a kraken?
They're on a ship in a manga; as certain as a 45-year-old man being struck by Mammophobia, a ghost pirate ship is required by the gods of trope.
Neither of which are at all interesting, but at least a "ghost pirate ship" is more realistic than any Japanese male (or really any male humanoid) flailing about in stark terror simply because he witnessed mammary glands existing....