The satellite 'KITSAT-1', who goes by the name Il-ho, is launched into space where she spends a long time observing Earth and over time becomes curious about the human heart. Kyung-chun, an aspiring musician, is heartb...展开roken when Eun-jin, the love of his life, starts to date someone else. The sadness he bears in his heart turns him into a milk cow. One day, Kyung-chun is tracked down and attacked by the Incinerator, which looks for people with broken hearts. At the same time, Il-ho falls from space and Kyung-chun is able to avoid immediate danger. During the fall, a magical force turns Il-ho into a human. She receives the help of Merlin the Wizard, who has turned himself into a roll of toilet paper, to find Kyung-chun. Kyung-chun fears for his life as he is chased by the Incinerator and the organ trafficker Mr. Oh. But Il-ho comes to his rescue whenever he is in danger. Gradually, the two become close and Il-ho slowly begins to understand the human heart. However, Il-ho realizes that she doesn't have much time left to live.