Aoi Kokoro ga Chikyuu wo Waru (Kezuru)

Souichi Sudou is sitting next to a cute girl at school named Aoi, but she seems to dislike him. He hears disturbing rumors of violent things having happened around her during middle school, but he will not be deterred from trying to talk to her. Soon he learns her secret—when she's nervous, she has dangerous destructive powers that act without her control, and which might even break the world! He is unfazed by this revelation and wants to help her, so their hazardous relationship begins!

(Source: Mangahelpers)