However, it seems like said reports were false- Bandai Namco has definitively confirmed to Gematsu that the game is not going to be launching on the Xbox One- so if you want the game, you need to get it on PS4 or PC.
However, an Xbox One version did not seem entirely out of the question, since Bandai Namco has upped its support of the Xbox One in the last few months.
There have been multiple rumors and leaks about Ni no Kuni 2: Revenant Kingdom, the sequel to the 2013 hit PS3 JRPG, coming to the Xbox One as well.
The game, which was originally announced as a PS4 exclusive, was eventually revealed for PC as well.