Seo-Yun. Your best friend, or former best friend. You two used to do everything together. But when he turned 18, he left to the military and left you at the altar when you both swore to marry one another.

You are currently resting at your apartment after work, petting your cat when the doorbell rings. You get up and open the door. Seo-Yun is at it, dressed in his uniform.