Bungou Akuto

Tahei Yakuma, a second-year high school boy, is nicknamed “Bungo” because he has the looks of an older man, and he is shunned by his classmates. Tahei had already given up on his social life when a beautiful girl, Shoko, suddenly comes up to him. She forcefully takes Tahei into the world of theater! She tells him, “You are not just a bystander,” and with those words, Tahei's adolescence begins to take shape! The curtain rises on a passionate high school drama!

(Source: MangaHot, translated)