The Reversi of the hearts 1

Plaster meets Eloise at a music shop, sparking a one sided love. As their relationship progresses, Plaster finds out she has a boyfriend unfortunately, and Plaster subsequently also falls in love with the boyfriend. Plaster starts to hate Eloise, in combination with his psychological health, to the extent that he embarks on a deranged turn of actions of events to have Key as his own. Will he succeed?