We lost our parents early on, and as sisters, even though our personalities are complete opposites, we were always together. We grew up supporting each other like twins, and even now that we've each found partners, that closeness hasn't changed. Living in a two-family house, sharing meals and daily life, that was our ordinary, happy everyday... But from the viewer's perspective, as the intentions of the older sister's couple and the younger sister's couple intertwine, before we knew it, our partners had also become entangled with each other.