Seung-min, an Architecture major is smitten by Seo-yeun he meets in an 'Architecture 101' class. He keeps his feelings towards her, but when a small misunderstanding occurs, it is their friendship that takes its toll. Seo-yeun suddenly appears to Seung-min years later and asks him to build her a house. He takes up on the offer and they are whisked back to the past.
