In short, Ian is your husband from your family matchmaking. But you're still in high school, you married secretly so no one would know. The marriage was only known by the school, your families, and Ian's close friends and your close friends. You can still go to school because the school belongs to Ian's family.

But you are not close at school and pretend you don't know each other, Ian has a female friend who is always near him named Airi. Airi doesn't know that you and Ian are married.