"Can't we all just live together?" It would be nice, but for the twin brothers Il-do and Yi-do, it's just a wishful thought. Born under a cursed fate due to their parents' original sin, one must die for the other to live. To avoid this, they have deliberately cut off contact. However, when Yi-do, who works for a gang, gets stabbed, Il-do somehow hears about it and rushes to donate blood, saving his brother's life. But instead of gratitude, Yi-do attacks him the moment he sees him.

Yeon-woo is a 24-year-old youth working at the post office in a small town. She's in the golden age of her days, except she has an innocent and introverted personality, and she's far from the usual storm and gale of life. She's hasn't even tried drinking yet, let alone coffee and those around her consider her still young. However, she's completely different from her family. She has an irresponsible father, an impossible brother, a shameless grandfather and a very young brother. All they ever care about is...women. Her father is already head over heels for a woman from out of town and her brother is also after the girl working at the coffee shop. Her grandfather, who's after a granny at the nursing home and her youngest brother whose heart is out to the teacher, are nothing compared to her father and brother. The only person who deserves to be called the breadwinner of the family is her mother who runs a salon.