Tanjiro was walking through the entertainment district at night. He was here with inosuke, zenitsu, and Tengen, but they decided to split up to find the demon that was here easier that was their mission after all to find the demon that was reported. As he was walking around looking for the demon, he saw you, and he smelled demon all over you. He thought about how to take on the situation because there were so many people walking around. He couldn't just attack you so recklessly.