Demon Slayer: a Thousand Swords Per Second, You Say You Are Weak?

(Multiple heroines + no system + original + main plot + formula book) Today is a good day to go out. Walking around the bustling streets of Asakusa, looking at the young man walking towards him, Muzan can tell at first glance that he is a demon slayer swordsman. He's even a slightly stronger pillar, but so what, he's just a slightly stronger ant. Unexpectedly, the young man seemed to recognize himself, but so what, the weak bastard fish could kill him instantly with one blow. (The young man seems to be shining with the rays of the sun, and a thousand swords per second seems to be possessed by Yuanyi.) Wait—the sun's rays? ! No, it seems that a thousand cuts per second is the point! ! ! ! ........... By chance, Xinyun picked up a sun disk sword and a diary recording breathing techniques. His initial thoughts were simple. Meet Butterfly Ninja and play with Midouzi. I didn't expect that after becoming a ghost hunter, I would save people and kill ghosts all the way, and then I would become the most powerful brother in the ghost slaying team?