With much similarity to the following songs..

YouTube - PSI-missing (http://www.youtube.com/watch?v=XLEazi--Og0)

YouTube - No buts! full (http://www.youtube.com/watch?v=kfUTmxB49M8)

YouTube - ON/OFF - Butterfly - Durarara!! Ending 2 Full (http://www.youtube.com/watch?v=K9E0X4Sq-6s)

Nothing that sounds too happy or too dark, similar to the tempo in the songs, and preferably involving electric guitars such as in the songs.