La Blue Girl (Series)

Miko Mido has fallen in love for the first time. Too bad for her that she hasn't the time to pursue the man of her dreams. There is a mysterious female ghost which is attacking Miko's schoolmates and stealing their life-force, and someone has to investigate the case. However, it seems that the ominous phantom is willing to pursue Miko's love interest, too... (Source: ANN)