Siwon's younger cousin Minju, moved to Korea due to educational reasons. Her best friends Eunhee and Mary moved to Korea with her. Hearing that there were 2 empty rooms in the dorms, they also brought Minju's younger sister, Shelly, along. Life was going smooth, until Minju lost her memory. Eunhee thought everything would be alright after the surgery. But on the other hand, Mary had a feeling that the path ahead of them wasn't easy. This is all merry-go-round.