Koe no Katachi
Based on a one-shot that won the 80th Weekly Shounen Magazine Newbie Best Mangaka Award.
Shouya is a bully. When Shouko, a girl who can't hear, enters his elementary school class, she becomes their favorite target, and Shouya and his friends goad each other into devising new tortures for her. But the children's cruelty goes too far. Shouko is forced to leave the school, and Shouya ends up shouldering all the blame. Six years later, the two meet again. Can Shouya make up for his past mistakes, or is it too late?
(Source: Kodansha Comics, edited)
Included Bonus Chapters: 1.5 and 38.5