Sekai de Ichiban “Kawaii” Amamiya-san, Nibanme wa Ore. (Light Novel)

Hikari, a highly popular model hailed as the "Cutest Girl in the World"... The mysterious model turned out to be an ordinary high school student named Harema Kouki! Kouki is troubled by the fact that he feels he's too cute when cross-dressing and can't find other girls cute anymore... But by a twist of fate, he realizes that his classmate, Amamiya-san, is much cuter than him—!?