Microsofts consoles are probably not the best place to play jrpg's, but ocationaly Microsoft takes a bit money to either get marketing rights to jrpg's (a lot atlus games) or spend money creating exclusive games. These exclusive games wer mostly produced at the time of the Xbox 360. One example would be Tales of Vesperia. Also The Last Remnant or Resonance of Fates would be two games that came out at that time and come to my mind.
Since the Xbox 360 Store will close soon, or probably already has been, i want to know what would be the best game you can think of for the Xbox 360 and let's hope there are enough ressources online to still get these games.
Also i heard of a game exclusive on xbox with sky ships that was exclusive and never got a remake/remaster or port? Someone know what i mean?
Blue Dragon and Infinite Undiscovery are both 360 exclusives and were well received. Neither have ever been available on any other system. I have both, but I've only played Blue Dragon so far. I haven't made a lot of progress yet, but it could be the game you described based on what I have seen.
i forgot the possibility to buy 360 games on the newer Xbox consoles. Seems all game mentioned in the comments are playable on Xbox one/series consoles. That's good.
If you show me Infinite Undiscovery novadays, i would even be slightly interrested. Blue Dragon seems to be another game with Akira Toriyama as Illustrator, as always nice style, i especial like the monster designs. Sad these game won't be that easly to obtain anymore.