Shakugan no Shana S01 E15 The Day when the Flame was Born

With Tendo-kyu, the castle Alastor and Shana resided in, destroyed, the time has now come for Shana to finally become the Flame-Haired Scorching-Eyed Slayer. However, she must first enlist the help of Tenmoku Ikko, a very powerful Mystes.