One of the most popular questions that comes up when it comes to the Kamado family in Demon Slayer is: what happened to tanjiro's dad? While he may have been killed in the Entertainment District arc, his influence on both his son and daughter continues to be felt throughout the show.
The late Tanjuro Kamado was the husband of Kie Kamado and father to her children Tanjiro, Nezuko, Takeo, Hanako, and Shigeru. He suffered from an illness that made his skin look pale and frail, but he was unwavering in his determination to achieve success for his family. Tanjuro also possessed a crimson forehead scar or birthmark similar to that of his son, which is believed to be a demonic mark indicating his extreme power and potential.
He also wore a pair of Hanafuda earrings, a family heirloom that has since been passed down to tanjiro. Despite not being a demon slayer, he taught his son sun breathing and other techniques that proved crucial against Muzan.
In the end, he was killed by Kibitsuji Muzan who was looking for the perfect demon and thought the Kamado family line, including Nezuko, had the potential to produce one. Sadly, he was wrong and the entire family was massacred. Regardless, he was a great man who influenced his children greatly and his memory will live on.