A new Weekly Jump scan introduces the mystery man at the upper right part of the game's box art, the same man that was in the recent third trailer.
This man clad in red is named Gaias/Gaius (????, gaiasu, romanization not official), and is regarded as "The Hero of A Jule" and also its current king. He is voiced byRy?tar? Okiayu, the same VA who voiced Dymlos and I think, Miktran/Kronos in Tales of Destiny/Destiny 2. He is designed by Mutsumi Inomata, and his line in the scan is "I will not perish, as long as I have the will to guide the weak." He unifies the northern continent with his charm and his power that does not seem human, he is a hero who has formed this mighty confederation/union.
There is also info floating around regarding the other mystery character in the box art. This info was supposedly from Weekly Jump, but since this is the only Tales-related info in this week's WJ, consider that info as false.