Sakamichi no Apollon/Kids on the Slope - 01
"Summer, 1966. Kaoru Nishimi has moved to live with relatives in Kyushu. He's been an aloof honor student his whole life, but that starts changing when he meets Sentarou Kawabuchi, the school's notorious bad boy. Through him, he learns the appeal of jazz and forms his first real friendships."

Jazzing teens.

Piano-egghead versus jazz-thuggabe gives omelette band.
Interesting clash of personalities.
Let's see, the manga was published in Shogakukan's "Flowers", it's slanted towards female teens and the like.
I wonder if that in-between girl (is she supposed to represent the viewer?) is going to blush too when the other male members of the band are introduced... Is she the actual main lead, and the four guys merely sort of elements of her harem?