Japanese warship candidates for an Azur Lane event

Which Imperial Japanese Navy ships or designs would make good additions to an Azur Lane event, and should paper ships be expected?

Paper ships are likely because most famous Japanese vessels are already represented; Number 13, I-401, and torpedo-cruiser concepts are the clearest remaining candidates.

Paper designs are expected because the game already includes most famous Imperial Japanese Navy ships. Number 13 is described as a 47,500-ton design capable of 30 knots, with four twin 18-inch turrets, a 13-inch waterline belt and 5-inch deck armour, planned for the 1920s. A ship with those characteristics would have alarmed rival navies. I-401 offers a historical submarine-aircraft-carrier choice, while Kitakami-derived or unbuilt torpedo-cruiser ideas provide other candidates. The torpedo-cruiser details are disputed, so the discussion does not settle a specific armament layout. These suggestions distinguish completed ships and serious unbuilt designs from additions invented for a game.