 If you liked
Shakugan no Shana
|
 ...then you might like
Ao no Exorcist
|
Felt the smiliarity directly when I watched the first episode of Ao no Exorcist.
Mostly the combinations of demons/torches/Guzes no tomogaras and exorcist/flame hazes. Thought in Ao no Exorcist there misses a opposite-gender main character but that probably will be filled up by Rin's brother Yukio.
Conclusion: Both have a mysterious story that you have to accept to continue and lots of action and a slight touch of comedy.
Both have protagonists who wield swords of fire, and both deal with two parallel worlds. The exorcists' job is similar to that of the Flame haze as they both fight demons in different ways.
Both series are set in a world where humans and monsters from another dimension co-exist. Both of the "monsters" of each respective series (demons in Ao no Exorcist & Crimson Denizens in SnS) feed on human souls, while there exists a special defence force of humans whose task is to hunt and kill them (Exorcists in Ao no Exorcist & Flame Hazes in SnS).
Additionally, both series' protagonists are sword-wielding fire users, hot-headed and members of each series' "defence force".