Prologue: Separation

While away from their small home on the top of Mount Kumotori in late August 1899, healthy charcoal merchant Tanjuro Kamado, his wife Kie, who is four and a half months expectant with healthy quintuplets, and their one year and one month old daughter Tsunami see newly widowed teen mother Kotoha Hashibira running towards a cliff with her infant son Inosuke in her arms from the sadistic and cold natured demon Doma. Both Kotoha and Kie are knocked out and taken prisoner by Doma a minute and a half after the freshly widowed teen mother tosses Inosuke from the cliff edge into the river below to save his life. After seeing this happen and yelling out his wife's name, Tanjuro flees with Tsunami asleep in his arms. Over thirteen years later, in late December 1912, Tsunami, who is now fourteen, and Tanjuro get home after a long day of selling charcoal to the residents of the nearby town and are immediately ambushed by Doma, who knocks out Tanjuro and captures him alive seconds after he chooses to stay behind to take the sadistic and cold natured demon on in a battle with his hatchet so Tsunami can escape and make her way to the Demon Slayer Corps headquarters with their family's sword in her possession. The morning after Tsunami makes it to the organization's headquarters alive, its leader recruits her as a demon slayer with the aim for her to become a pillar after telling her the truth. After several months of regularly taking out demons at night, Tsunami becomes the sun pillar two and a half hours after winning a nightlong battle against a stronger demon and returning to the Demon Slayer Corps headquarters. That night, she and the flower pillar Kanae Kocho are sent with a wooden cart to the temple almost a hour after Doma leaves for the night and get the rest of the family and Kotoha out of the temple, sneaking into it through a plastic window.