This is a love story that gives pure love. Go Mi Ran and Ma Dong Chan participate in a experiment that changes their lives forever. The story is well-written and has fully developed characters. It provides a sweet romance with a good mystery. It kept me guessing and added subplots that complimented the main story. The ML and FL were excellent. The chemistry was EXCELLENT. The slow burn of their romance was believable and worth the wait. Go Mi Ran is one of the best female characters I've watched in a K-Drama. She is feisty without being annoying. She showed confidence and strength. The actors did a wonderful job building their characters. The cast was good. Highly recommend since I've watched it at least 5 times. I do agree with others that the ending was lackluster but I find that is common in Kdramas.