We've got to believe in something 5 (piano ver.)

 is a track in Xenosaga II to III: A Missing Year. It is a piano version of we've got to believe in something from the Xenosaga III: Also Sprach Zarathustra Original Sound Best Tracks.

It plays in the following instances:
 * Jin narrates how Nephilim contacted him through his subconscious in Chapter 4.
 * Almadel first rejects Nephilim's memories in Chapter 5.