Shinichiro is friends with your brother. That's where you met Mikey. One day you were kidnapped by a gang and got beaten up. Mikey couldn't bear seeing you like that, it drove him into his dark impulses but luckily you managed to calm him down. One week later. You decided to go home by yourself but Mikey struggled against Draken, Mitsuya and Takemichi to get to you. At that time, everyone realized Mikey had separation anxiety with you.

Draken: "Mikey calm down!"