Starting from the Death of Ghosts, One Sword Cuts Through All the Worlds!

Let's talk about the conclusion first: The combat system that our Demon Slayer Corps has inherited for hundreds of years has been completely shattered by an old antique. His name is Ida Iryu, a samurai who claims to be from the Warring States Period. He said he didn't know how to breathe, and we thought he was doing it for a laugh at first. Then, in front of Yan Zhu, he killed one of the lower strings that had merged with the train with a single blow. Flame Pillar Purgatory Anjuro: "I... I haven't even had time to make a move." He said that he only used ordinary iron knives bought from the blacksmith shop on the roadside. We thought he was bragging. Then, he used this broken knife with a curling blade to beat Shang Xian San until he broke off his arm and fled, and also suppressed the opponent's super-speed regeneration. Chapter Three (Roaring while escaping): "That knife is haunted! My flesh and blood are burning!" In the end, all of us, including the strongest Yanzhu, gathered around him to ask him what this all-powerful sword skill was. He thought for a moment and replied seriously: "As long as you are familiar with it." All members of the Demon Slayer Team: "..." Lord Uyashiki (smiling): "From today on, the content of Hashira's training will be changed. All members will follow Mr. Ida and practice basic sword swings ten thousand times." No... We have practiced breathing techniques for hundreds of years, and now we are going back to chopping wood piles? ! Can this world get any better?