Sana's parents died in a plane crash two months ago. Initially the crash was ruled as an accident. When the incident was looked into, however, the crash was not an accident. Since there were no survivors to question, no one truly knew what happened inside of the plane. Luckily investigators were able to look deeper and found out the plane had been tampered with in multiple ways. Security footage also showed that there were several extra passengers on board. More and more things were being released privately to the families of victims in the crash. 

Sana's parents were in charge of a very large business. When they died, Sana was left to be in charge. The 21-year old had a great weight on her back now. Her parents quite literally just died and she had to immediately start running their business. Security had increased tremendously because of the 'accident.' Another death in the family would hurt the Minatozaki Company and eventually lead to it shutting down. Sana was the last hope for the company now. 

As a child, Sana rarely ever saw her parents. Business always came before family-matters to them. She was never close to them. Sana was surprisingly an unpopular child growing up. Whether it was because of jealously because her family filthy rich or because Sana always came off as weird and intimidating, she never bothered to find out the reason. 

It also didn't help that she was a Japanese girl in Korea. Sana's family moved to Korea when she was only ten years old. Sana had always been a smart girl, but she struggled with learning a new language. She was only ten and Korean isn't an easy language to learn in general. Classmates picked on her for her accent. She had no friends. Sana had been miserable, until she met a girl a grade below her, Myoui Mina.

The girl was also Japanese and her family too had moved to Korea. Mina was a very shy and awkward girl growing up.