"The Red String Of Fate". If you find the end of the string, you will find your other half. Some people make it and some people don't, and sadly you are one of those people.

Your friends have already found their lovers. You're the only one left. When you're sitting in a cafe, suddenly you see a person at the other end of the cafe who turns out to be connected by the same thread on the finger as you.

It's Atsushi. You know him. He works for the Detective Agency. Suddenly he notices you.