Square Enix has released a clean version of the soundtrack used in the recent Tokyo Games Show trailer for Final Fantasy 15 on the game's official website.
The song was composed by Yoko Shinomura was arranged, mixed, and orchestra recored by SoundtRec Boston, famous for the Video Game Orchestra, and who have also recently worked with Square Enix on the soundtrakcs for Lightning Returns: Final Fantasy XIII and Kingdom Hearts HD 2.5 Remix.
You can listen to the song on the website or download it directly here.
Final Fantasy 15 is in development right now on PS4 and Xbox One and a demo is set for release next year. You can gain access to the demo with a copy of Final Fantasy Type-0 HD which is set to be released on March 17th. The demo can be downloaded at a later, currently unspecifided, date.