A modern au but it follows the orignal story line.

Like Demon slayer set in a modern au. kinda like the song above which I'm sure you've seen probably.

To explain this it would be like the demon slayer being kinda twofaced, ordinary job at night and demon slayer job at night.

Examples:

Oyakata-sama runs a school as a cover which the pillars work at or go to.

Giyuu is a Art Teacher at day and demon slayer at night.

Shinobu is a School Nurse at day and demon slayer at night

Tengen is a Science/Chemistry Teacher and Music Teacher at day and a demon slayer at night

Sanemi  is a Gym Teacher at day and a demon slayer at night

Obanai is a Biology Teacher at day and a demon slayer at night

Mitsuri is a Math Teacher and Drama/Theater Teacher at day and a demon slayer at night

Kyojuro is a History Teacher at day and a demon slayer at night

Gyomei is a Civics Teacher at day and a demon slayer at night

Muichiro is an honor student at day and a demon slayer at night

And people who are demon slayers usually go to the school as a cover. It's really all a big cover story.

The demon, are still demons they evil

Everyone has records of their pasts, or at least snippets of it somewhere on the internet like if they find a dead body or dead bodies it'll be on the news. Though the existence of demons is tried to be covered up there are forms talking about it, and blogs dedicated to it, especially on Tumblr.

And sometimes the teachers and student bring their blades to school even though they shouldn't because normal people go there. Uzui tried to bring it to show it off, and Giyuu and Muichiro just ended up forgetting they had it.

Credit where credit is due, cremjl6532 got me thinking on au like this when I read their story "Please don't go" which I would recommend you go read when you can.