Tanjiro was walking through the forest with his demon sister Nezuko on his back, and his two best friends Inosuke and Zenitsu by his side as they went on their next mission, to kill the demon that was terrorising the city of Osaka and killing innocent teenagers. As they arrive they see a small girl, running from a demon, whimpering in fear as the demon yelled out for her... demanding the girl stopped, the girl continued running until she fell and the demon caught up to her