Nightmare Eater

From AOC Translations: Kanomiya Tsukuru has a special ability since childhood. He can see the manisfestation of someone's misfortune in the form of a blackmist, and he can even purify them. Kanomiya has spent most of his life keeping his ability a secret, but on the day of his high school entrance ceremony, he sees a beautiful girl, Arisu Howl, emitting a special kind of blackmist. Smitten with her beauty, and worried for her future, Kanomiya stalks Arisu..! A beautiful excorcist and a wimpy sidekick, an action-packed supernatural school adventure begins!