Manga Idol and bodyguard

Mc (a bodyguard) was assigned to guard an idol who was stalked by an obsessive fan. Turns out this idol was his fan and even has his photo hanging in his room.

They met when the idol was in highschool at the bar. As they were trying to hook up, Mc realize he was with minor and shut him down. But then he gave the idol a word of encouragement and that's why the idol is a fan of him.