Does she have long red hair? If yes, then that's Elfen Lied. I may be thinking of another show here, but I'm pretty sure that The Melancholy of Haruhi Suzumiya is light-hearted. It's just the premise of the show that's scary.0p3rati0n said::O your not kidding! That is creepy! Wait i've seen scenes from youtube videos where a girl just walks past people and they explode! Is that the same thing or different?????
EDIT: Ninja'd getting a snack. Damn...