Do you remember when...?

Ren is moving forward. But not moving on. Three years after the Phantom Thieves disbanded, he has a good life. He's studying, he has his own place, he managed to come back to Tokyo, and some of his friends are even at the same uni. But everyday, he feels the hollow space where someone is missing. His friends urge him to forget, but how can he forget when he is the only one that even remembers? That cares?One evening, nearly three years after The Day, he goes home without noticing the stranger following him. Until it is too late, and said stranger is standing in his hallway.