Speaking with Glixel, Level - 5 CEO Akihiro Hino (who's also the game's writer) explained why the company decided to provide a completely different cast of characters and a hugely revamped battle system from Ni no Kuni: Wrath of the White Witch. (wccftech.com)
The trailer showed a hugely different visual style to the original game (to be expected), and teased a completely different cast of characters and themes. (gamesradar.com)