Shakugan no Shana EP4 - Flame Haze of Illusion

Yuuji and Shana seem to be getting along well and she unexpectedly sleeps over, in his room. The problem is that Shana starts to feel differently about this Torch (Yuuji) than any other, could she be developing feelings for him? Meanwhile, another Flame Haze arrives in the city. What is this person's motive?