Demon Slayer: Kimetsu No Yaiba, Rebirth at the Beginning to Save Kanae

"This time, I want everyone to survive." In the final decisive battle of the Demon Slayer Squad, Mukai was wiped out, but at a heavy cost - Kanae, Shinobu, Infernal Anjuro, Muichiro, Genya... Died one after another in front of Kaguya. When Kaguya herself fell in a pool of blood, unconscious, she heard a voice: "Strong regretful obsession was detected, and the [Regret Recovery System] was activated. Time coordinate: three months before the attack on Butterfly Kanae. " Reborn and returned to the starting point of tragedy, with the memory and mysterious system that predicts the future in hand, Kaguya vows: In this life, not only will she save Kanae, but she will also change all the difficulties. But the butterfly wings have already flapped, and the fate he has changed is quietly triggering a terrifying backlash that even the system cannot predict...