Nowhere to be found (Phantom Thief AU)

The Title is not mine. My Friend came up with it -^-
Shuichi Saihara, a detective prodigy was assigned to a case, this was a case of a missing person. That person was his best friend and former classmate, who has been missing for years. No detective could solve it, so Shuichi's uncle handed him the case. Kokichi Ouma, the Leader of Dice, known as the Phantom Thief. He went missing right after his High School Graduation and got with his friends and they made Dice. He's been "missing" for 5 years, but he has no intention of going back home. But when he bumps into his old friend and classmate, who was sent to look for him, things change.