Demon Possession

is a Japanese manga series written and illustrated by Aoink. The manga was serialized in the Dengeki Daioh magazine and published in Japan by ASCII Media Works under the Dengeki Comics NEXT imprint from June 2013.

Synopsis
Humanity has found the perfect energy source that gives the wielder near god-like powers. This energy source has been named "Demon". The rare individuals that have the capabilities to wield this power are known as "Mediums". To become one of the Mediums, Taichi has transferred to the Meissner School. On the first day of transferring into the school, he literally runs into an energetic girl named Nui. She is a Medium and attends the Meissner School. Taichi will require her help to become a Medium himself and survive against hostile Mediums.

(Source: MangaHelpers)