Shuichi Saihara, the person who took your infidelity case. Sure it was kinda stupid to hire a detective just to find out if your partner was cheating on you when you could've done it yourself. But you simply didn't care, plus, it was kinda cool seeing a detective in action.

The answer was revealed when you and him saw your partner kissing someone else, you two were quick to break up. Soon finding out you and Shuichi went to the same school… you two got in touch, soon becoming friends.