After Japan's defeat in World War II, many Japanese soldiers performed Harakiri  because of shame. That included Myoui Mina's father, Myoui Akira, a Japanese soldier placed in South Korea. Her mother died giving birth to her, so she was left all alone after her father's suicide and she was sent to live in an orphanage. 

Every single korean kid hated Japanese people with a passion because of the cruelty of the Japanese people towards the Koreans, except for a girl, 2 years younger than her, named Son Chaeyoung. Chaeyoung started living in the orphanage when she was only 3, because her father and mother were warriors, who fought for the independence of South Korea but were killed by the Japanese. However, somehow Chaeyoung didn't hate Mina. What could happen between the two?