Toaru Kagaku no Railgun Gaiden: Astral Buddy

Hokaze Junko, one of the top "handmaidens" of Shokuhou Misaki, has always blended into the background of Tokiwadai–an easy feat when you go to an all-girls' school full of powerful psychics. But when a ghostly figure starts stalking her, Junko is suddenly the center of attention! As Junko investigates her stalker, she starts to learn new things about her classmates...and herself!

(Source: Seven Seas Entertainment)