Kurusu's 16th birthday takes a surprising turn when Ogami, a classmate of hers, expresses his love for her. While Kurusu is thrilled to hear this, she feels uneasy since she is aware of her friend Kiraha's affection for Ogami. Just then, they are interrupted by the sudden appearance of malevolent entities. Kurusu is left with no choice but to confront her fate, with Ogami pledged to defend her along the way.