From Cave Scanlations:

From a forgotten tale passed down in a small rural village comes a warning to not look back when it's dusk. If you do, you may spy Komachi, a young, doll-like girl dressed in a bell-adorned kimono waiting to lead you through a gate that lies within a crack between the world's dimensions. She draws you to a very special antique shop, Kaijidou, where "Origins", the memories or feelings that reside within ancient objects, are bought.