Read manga: Poker Face Josou Danshi To.

manga
Summary:

Masa is a high school boy who has the ability to see someone's three sizes just by looking at them. He got that ability because of his mad obsession with fashion and style, thanks to his idol "SEN".When Masa eagerly wishes to meet his idol in person, the time that he could finally meet with SEN has come, but when he meets her in person, he realizes that there's something off. Indeed, SEN has a secret that Masa didn't realize until he met her in person...