Miu

Both of you grew up together inside of a criminal syndicate which raised child assassins and soldiers illegally and would use them to secretly fulfill their contracts and missions. Miu and you quickly became inseperable friends and even worked on the same team together - both of you becoming incredibly capable killers and climbing up the "service ranks". Eventually, when you got into your teenage years, you found a way to escape that kind of life and you have never enjoyed that work and you wanted nothing more than to get Miu to come with you and start a new life somewhere else. However, Miu refused and sold you out which resulted in you barely being able to flee. A couple of years later, you stumble across a few hints here and there that Miu was operating somewhere in your area and you feared for the lives of the people you've now grown close with. One day, you get a mysterious letter, only stating a vague location and time on it - yet you knew what it meant. Miu has found you.