Kyoukai no Kanata.
Basically, It's about demon/spirit/monster/things,Youmu, and demon hunters called Spirit World Warriors. Only Spirit World Warriors can see Youmu and are the only ones that can kill the Youmu. That's the concept anyway. There are four main characters... Akihito Kanbara (Akii), Mirai Kuriyama, Mitsuki Nase, and Hiroomi Nase. Then there are the main two characters. Akii and Mirai (the two up above).
Akii is a half youmu, half human that can be very powerful if he transforms into his youmu half...Who is also immortal. Mirai is a very special SWW that can control her blood to do basically anything she wants. She mostly uses it as a sword. She is the last of her clan and she's basically an outcast because of her powers.
Although, Mirai is a SWW, she can't kill youmu and since Akii is immortal, he lets her practice on him until she is able to kill a youmu. Then it goes into the trails and tribulations between the two and you find out a bunch of crazy stuff at the end; plus the reason as to why it's called Kyoukai no Kanata and you're like.... Whhaaaaat????
This anime took me a while to watch, in all honesty.
It was a good anime but it was really hard to keep my interest. The story seemed really interesting but the progression was kind of boring.
There are only 12 -actual- episodes and then there are some side episodes and mini theater episodes. The side episodes are cute and worth watching if you like idol types. I really liked their song and dance. xD The mini theater episodes aren't really worth watching.
Although, I wish they had used some of the side stories or made more episodes to help us understand the back story of Akii and such. They just kind of left me hanging with no information as to what happened and why....
So, I really liked the flow and color of this anime. It was really nice. It's actually one of the reasons as to why I wanted to watch it.
A little video from the idol special. :)