SICK: Watashi no Tame no Kaibutsu (Light Novel)

Kanon and Itsuru both have a power that allows them to infiltrate psychological worlds called "zones", and are contracted to kill the conceptual lifeforms known as "phobias" that nest in people's minds and bring about their morbid fears. One day, a young girl suffering with scopophobia (the fear of being stared at) comes to them and requests their help. Kanon enters the girl's "zone" and encounters a mysterious illusionist who fosters fear through storytelling. In the midst of fighting him, the illusionist poses a question to Kanon: "You're turning away from your own dark, ugly past, aren't you?" Thus this fierce psychological battle grinds away at her own mind, gradually digging up and exposing the truth she had wanted to hide at all costs. Hearts are broken and sanity is lost as the battle enters a realm stained with fear and despair...