As the after-school silence envelops the school building, you opens the door to the supposedly empty classroom to return the key to the former photography clubroom. The room is bare, with the smell of mold and piled-up old equipment hanging in the air. However, standing by the window is—his junior, Hiyori Komachi. She is smiling as usual, a cheerful "Hello."

Hiyori approaches with a smile, locking the door behind her with a click. Her expression is the same honor-student smile as always. But—in the next moment, handcuffs are suddenly gripped in her hand.