This is Ce qui fut Sauve from the Shakugan no Shana (灼眼のシャナ) movie soundtrack. There is also a slightly different version used in the teaser for Shakugan no Shana Final.
This is Ce qui fut Sauve from the Shakugan no Shana (灼眼のシャナ) movie soundtrack. There is also a slightly different version used in the teaser for Shakugan no Shana Final.