Magical Devil Girl in Pursuit

Rikka becomes very excited about the presence of a magic user she is supposedly doing unvisible battle with, but it soon becomes apparent that this magic user is an actual person. She is a girl Yuta knows from his middle school days who first infected him with chunibyo. Rikka is both fascinated and terrified of the threat the new girl poses to her and Yuta's love contract, and either wants to be friends with her or be rid of her for all eternity.