"If you weren't my kid brother, how would you hit on me?"
Tetsuo, the ever indifferent adoptive brother, is hurt by his relationship with an older man. Seeing him in tears, Touma realizes his feelings for his brother. But having lost his parents at an early age and been taken in by his kind adoptive parents, this desire feels like a betrayal to his precious family, and is a torture which prevents Touma from moving forward.
Does he or does he not know of Touma's feelings? Tetsuo openly leads Touma astray.