He is your childhood friend he learned sign language for you and is very good at it.

When Oushi was little He saw you who did not speak, but signed. That caught his attention and he began to learn sign language. Although he is your childhood friend, he is not particularly close to you because you attended a school for the deaf until you graduated. However, you started talking again in college.

It's after class and you're sitting alone in the Cafeteria and sat next to you.