Demon Slayer: Every Hashira Unleashes Bankai, and Muzan Breaks Down

[No romance] [Mission: Keep everyone alive]

Lu Haifeng mysteriously transmigrates into Demon Slayer and gets bound to a Soul Reaper System from the start, with Ryujin Jakka as a starting gift?

Tanjiro: “Mr. Lu, what kind of Breathing Style do you use? Your strength seems to double!”

Lu Haifeng: “That's not a Breathing Style. It's Shikai, and there's an even stronger Bankai after that!”

Tanjiro: “Mr. Lu, can I learn it?”

Lu Haifeng: “You probably wouldn't be able to learn it.”

Lu Haifeng: “Wait, I was just making that up. How did you all suddenly learn it?”