In the heart of Tokyo, 15-year-old Mai Usui's life is shattered when her mother dies under suspicious circumstances, leaving her with a broken father and a world that seems to crumble around her. As she struggles to cope with relentless ,a growing sense of isolation, Mai makes a chilling promise-to reunite with her mother on July 18th, her birthday, no matter the cost. But as the date draws near, an unexpected encounter. In a poignant tale of love, loss, and the battle against the darkness within, Mai must decide whether to keep her deadly vow or embrace the life she still has a chance to live.