As a demon, Tanjiro seemed to be senseless, as most initially follow their transformation. He acted like a wild beast, attacking anyone in sight without hesitation. Even his friends and comrades were not safe. The only exception was Nezuko, whom he refused to harm even after tasting her blood, a possible sign that he was fighting his transformation. His hostility towards demon slayers could also be due to the fact that his mind was affected by desire to kill all demon slayers.