Very loosely, it will feature a completely different plot and all new characters. Sort of like the way FFXII is related to FF Tactics and Vagrant Story.
They were related previously, sharing the same mythology and possibly the same world, but ever since VXIII got renamed XV it looks like they're going to make it a standalone game. This is because Enix wants to make the distinction between the Lightning Saga and other games clear (same thing happened with Agito XIII being renamed Type-0). -- ∙ ∙ 04:10, August 9, 2013 (UTC)
It will. But not necessary directly. The only confirmed conection between both games (or universes) is that both are from the "Fabula Nova Crystallis" series. Although there are rumors that there will be l'cies and fal'cies like in every other installment in the sub-series, like Type-0 and XIII-2. If that's true, then we can say it will be the first main game to be extremely similar to another main title. So, in the end, it is related, but just in things outside of the story or the game itself. GestahlianChocobot (talk) 07:15, August 9, 2013 (UTC)