In an uphill house of Kamado, where the Kamado family lived, there's a child called Tanjiro Kamado. He has 3 little brothers and 2 little sisters, his family occupations is a charcoal burner and charcoal seller. He has been grabbing woods for charcoal as normal, his father deceased long time ago so he lived with his mom, Kie and his siblings, until one day, he went to find some wood but a demon attacked and killed his family, when Tanjiro came back, he's shocked and cried about his family. He couldn't believe it, then the Water Hashira, Giyu met him, because he heard the news of demon attacks, he quickly consoles him "Don't worry, Tanjiro. I knew you are sad and depressed about the situation, but you needed to walk past it and became stronger." "I wanted to kill it, I wanted! It took my family away, I needed revenge and I don't want to see innocent people got killed by the Demons again!" Giyu saw his goals and his passion to cleanse the demons from Japan, so he took him to the Demon Slayer Crop, to get him as a member of them. Soon after, Mister Ubuyashiki accepted him as the new Demon Slayer. He got sent to train with the Water Breathing Cultivator, Sakonji Urokodaki. Sakonji is a former Demon Slayer and now he's retired from it. Tanjiro learned with him for 2 years and now he's successfully promoted to the reserve squad.
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Then he met his 2 new friends, Zenitsu Agatsuma and Inosuke Hashibira. Both of them have the same age, but they uses each Breathing Style. Zenitsu using the Thunder Breathing Style and Inosuke uses Beast Breathing Style. "Oh, I'm Tanjiro Kamado, I'm the new members of the squad and I'm using the Water Breathing Style. Nice to meet you, Zenitsu and Inosuke!" "It's nice to meet you too, Tanjiro. I'm Zenitsu Agatsuma, the Thunder Breathing Style user." "And I'm the King of Mountain, the Beast Breathing Style user, Inosuke Hashibira. Nice too meet you too, Konpachiro!" "Wait- It's Tanjiro!" Inosuke has a little problem about pronunciation. After that, they're all training together and waiting for their first mission.