Chapter 2 - How he survived

They killed him.or so they thought.after the anti-dot was injected into Tanjiro,he returned to his humanity and muzan was said to be finally finished along with all the upper ranks.they lived on to their happily ever after but they were not aware of what next would happen.before The fight, muzan had left one of his hearts in the infinite castle.so, after they had done away with him in battle, his heart began regenerating.of course it took time for his body to be fully regenerated.he still couldn't walk under the sun.so he waited for the next two -hundred years before attacking again.this time,nichirin swords no longer worked on demons.he made the new and powerful era of demons.some which had power similar to his own.he seeks to bring down humanity for an era of demons.will he be able to fulfill his goal? now especially with uzuki, the descendants of the other demon slayers?