The Adoptive Father of Every Demon Slayer Hashira, and Lady Muzan's Devoted Husband

Bai Yunfei transmigrates into Demon Slayer and runs into Lady Muzan from the start. What should he do?

Agree to let her grant him eternal life, become a demon, and serve her?

No! He'll remain human and make her willingly take him in!

Lord Muzan, they're bullying me!

After turning into a demon, Muzan grants him the title of Upper Rank Zero.

As a demon, why drink human blood? Drink demon blood!

Drink the blood of Ubume, Tamayo, Nakime, and Daki.

Lord Muzan, I haven't tasted your blood yet!

Bai Yunfei pulls open Muzan's kimono and bites down.

…

What? There isn't a single Hashira in this new era? Gyomei hasn't become a Hashira yet?

Then I'll be the first Hashira! I'll settle for being the Gold Hashira!

With 36 Breathing Styles, he becomes the master of every Hashira.

…

What? New demons have appeared?

They call themselves the Twelve Zodiac Demons?

Rat, ability unknown. Ox, ability unknown.

Tiger, ability unknown. Rabbit, ability unknown.

Dragon, ability: lightning. Snake, ability: ice.

Horse, ability: magma. Goat, ability: swamp.

Monkey, ability: puppets. Rooster, ability: storms.

Dog, ability: splitting. Pig, ability: strength.