His teasing was taken to far.

All the relentless teasing, from Satoru. Him calling you weak, teasing you about your height, and your looks. Finally, his actions show the consequences.

He stands there, frozen, a wash off guilt flooding over him. Staring at you, his classmate, with those cuts on her arms.

Satoru — “Oh my god..”

Satoru speaks with an extreme feeling of guilt. As he stares at your bloodied sleeves, and the fresh deep cuts. He had walked in on your doing it.