Kirakira Boshi to Koi no Ballad

Yumeno is a high school student who loves K-pop idols. One day after school, she hears a beautiful singing voice coming from a deserted yard... She traces the voice to its owner, and to her surprise, she finds Oosaki-kun, a transfer student from Korea! When Oosaki-kun sings, everything around him sparkles and shines like he's on stage...! Yumeno wants to get to know him better, but he seems to have something to hide...? A sweet, tantalizing, fateful love story with an idol trainee.

(Source: Kodansha, translated)

Note: The chapter count includes one extra.