What is the song that plays when Lelouch sees the memories of C.C. in episode 11?


In _Code Geass: Hangyaku no Lelouch_ episode 11, around 16:00 mark, there is a
song that starts to play when Lelouch sees the memories of C.C. Again, in the
same episode at 19:50, the same song plays for the second time.

I didn't recall hearing this song before episode 11, and episode 13 at 7:35 as
well.

I couldn't find the soundtrack from OSTs. What is it?




It's an unreleased piece from the soundtrack called **Sins and Astonishment**.
You can find it here:

[Code Geass: Unreleased Album - 07 Sins and
Astonishment](https://www.youtube.com/watch?v=BGJCiW2HL74&list=PLb4mticUuCmQSnQpXJDttkzbhOxAdnGWf&index=7)

