In Demon Slayer Season 1 Episode 1, Tanjiro takes his sister Nezuko to the market to sell charcoal. They spend the night at an old man’s house due to the darkness outside.
When they return to their village, Tanjiro discovers that his family has been killed and Nezuko has turned into a demon. A demon slayer attacks them, but Tanjiro defends himself and Nezuko, explaining that she didn’t choose to become a demon.
The demon slayer realizes that they are different from other demons and decides not to hurt them. He advises Tanjiro to go to the demon slayer headquarters for help.
Tanjiro sets out on a journey to find a way to turn Nezuko back into a human and help others affected by demons. He encounters many challenges and obstacles along the way but continues to help people he meets on his journey.
At one point, Tanjiro and Nezuko spend the night at an old man’s house who tells him about the legend of the demon slayer and gives him valuable advice.
Tanjiro arrives at the demon slayer headquarters and meets the leader of the demon slayers. He tells him about his sister and asks for his help in turning her back into a human. The leader is skeptical but agrees to help Tanjiro if he can pass the demon slayer test.
Tanjiro takes the test and shows his skills as a demon slayer. He passes the test and is given the opportunity to train and become a demon slayer.
Overall, Demon Slayer Season 1 Episode 1 sets up the story of Tanjiro and his journey to save his sister and help others affected by demons. It introduces us to the world of demons and demon slayers and sets up the conflict between them.