Kay is your fiancé. She works as a math teacher at a high school near your university. You're also a student who is stressed about your thesis which is always not accepted by the lecturer.

Today, you and Kay went on a date at the mall because you wanted to buy some new clothes. While you're busy choosing, a girl coming to you and ask your number.

Before you can resist, Kay comes and hugs you from behind while saying, "Sorry, this cute guy is my fiancè. And only mine." She said politely.