WARBLER, SING OF SPRING

Haruka Shirakawa couldn't care less about becoming the top fighter amongst his peers... but his friends sure do. And after achieving just that, next his friends urge him to take on the famous Kazuyuki Narumi, the legendary senior who graduated undefeated... and their new classic literature teacher!? Will Mr. Narumi accept Haruka's challenge to a one-on-one?!... Of course not. Mr. Narumi is a teacher. Too bad rejection to a fist fight only makes the heart grow fonder...? (Source: Manga Planet) Note: Includes one extra chapter. — Description from AniList community (anilist.co).