Reminiscence (XS1)

 is Disc 1, Track 6 on the Xenosaga Original Soundtrack and Disc 2, Track 5 on the album. ('Reminiscence' is an unofficial translation, as seen in the VGMdb listing of the album.) Kokoro (and by extension Kokoro instrumental) are both remixes of this piece, and Game Over, Shion ~Memories of the Past~, and Shion ~Emotion~ are all based upon the melody at the start. Shion's Crisis also uses the melody at the start as a motif. Finally, the melody at the start of The Girl Who Closed Her Heart and is similar to that at the start of this piece.

It plays in the following cutscenes:
 * Shion and Kevin talk the night before KOS-MOS's planned awakening (flashback).
 * Shion reveals she was from Miltia in the Realian Maintenance Room on the Woglinde.
 * Shion and KOS-MOS reassure MOMO about her origins and Dr. Mizrahi in the Durandal's park.
 * Kevin tells Shion that KOS-MOS has been exhibiting emotional behaviour (flashback).
 * Allen and chaos talk about Shion's emotional reticence in the Durandal's park.