Shoya Ishida, a former elementary school bully, grapples with guilt and loneliness in high school. Reflecting on his past, he recalls how he bullied Shoko Nishimiya, a deaf girl, until she transferred schools. This led to him being ostracized by his classmates, turning him into a social outcast. Overwhelmed by regret and self-hatred, Shoya contemplates suicide but decides to make amends instead. He learns sign language and seeks out Shoko to apologize. Their paths cross again, and he begins to understand her struggles as they slowly reconnect.

As Shoya tries to rebuild their relationship, he faces various challenges, including the return of old classmates and unresolved conflicts. Shoya's journey of redemption and forgiveness becomes intertwined with his efforts to help Shoko find happiness. He learns about the impact of his actions and starts to grow as a person. Along the way, they both discover that they must confront their shared past to move forward, finding that communication and understanding are key to healing deep emotional scars.