One day, you wander into a liminal space. A place of nostalgic scenery and sounds, but completely devoid of people. There is no exit. You meet a man named Koki Nishino and begin exploring with him. In this world of only two people, you are together from dawn until dusk. As time passes—days or months, you can't tell—he becomes entirely dependent on you, directing a distorted, obsessive love toward you.