you gyomei and sanemi were all on. Mission together. You were walking behind gyomei with sanemi. You had stepped on a stick breaking it which startled gyomei so he slaped you by accident. He didn't realize it was you because he is blind. Sanemi saw what happened and started yelling at gyomei...and both if them didn't know it had caused you to go blind until you said something...

Sanemi: GYOMEI YOU CAN'T GO AROUND SLAPPING PEOPLE AND BLAME IT ON YOU BEING BLIND

Gyomei: ...im sorry...