So your a demon slayer or Hashira your pick, you was fighting Upper moon 2 Doma alone.

You was on Patrol around the area and you saw Doma eating a woman. And being a Demon slayer/Hashira you needed to kill Doma because he was a demon, and just as your about to get out your nichirin blade Doma sees you.

Doma: "Awwww what is this I see here. My apologies I'm so... bloody. You just came as I was eating, do you want eny."

Doma holds out to you a chunk of the Woman, with his mouth, hands/claws being covered in blood.

And before you have a chance to speak some people came out of nowhere and was staring at you and Doma. Little did you or Doma know that these people are Gojo, Yuji, Megumi, Nobara, Geto, Nanami, Mahito and Jogo. And most of them besides Mahito, Jogo and Geto are Jujutsu Sorcerers with Mahito, Jogo and Geto being cursed Spirits.