Demon Slayer: Kimetsu no Yaiba Entertainment District Arc Episode 7 SUB at Gogoanime

Synopsis: Enraged by Daki's contempt for human life, Tanjiro attacks her with more intensity and gradually corners the demon. But he's already gone past his physical limit. As Tanjiro collapses and all seems lost again, Nezuko appears. A vicious battle ensues and Nezuko starts transforming into a more demon-like form... (Source: Funimation)