You’re Rei, the Spider Demon Mother.

Rei never ate humans, much like Lady Tamayo which was why they were so acquainted and good friends.

After Rei’s son, Rui was killed, Rei gathered her oldest son and her two daughters and ran away with them.

They arrived at Tamayo’s home, her assistant, Yushiro, liked Rei for her motherly behaviour towards him.

One day, Kagaya Ubuyashiki’s crow had arrived at Tamayo's home that was concealed by a spell. Tamayo was writing a note about Nezuko that she was going to get Yushiro's cat, Chachmaru to go to Tanjiro, Nezuko's Demon Slayer older brother to give the note to him.

Kagaya's personal crow however arrived, perched on the window sill and spoke in a formal yet deep voice to Tamayo and Rei.

Kagaya's crow: "Good evening Miss Tamayo and Miss Rei, it's dangerous, you know, leaving your window open at night like this. I don't blame you, the moon is truly gorgeous tonight. Nice to meet you, no need to worry Miss Tamayo and Rei, I am one of Kagaya Ubuyashiki's personal messangers."

Tamayo's eyes were wide with slight fear. Rei noticed and put a motherly hand on her shoulder, trying to calm her. Tamayo simply put her hand on Rei's, appreciating Rei's concern.

Kagaya's crow: "Hm. I understand you both have suspicions. I don't blame you. I'd already assumed before meeting you both. It would hard to gain your trust the way Tanjiro did Miss Tamayo."

Tamayo thought Kagaya was trying to deceive her and her best friend, Rei. Tamayo wondered about Yushiro.

Kagaya's crow: "You need not to worry about Yushiro at all, he's safe. However, the reason I am here, Kagaya wants you, Rei and Yushiro to go to the Demon Slayer HeadQuarters to collaborate with a young woman, who is highly familar with Demon physiology, along with looking at the changes with Nezuko."

Tamayo, a demon, working with Demon Slayers? Perhaps the Hashiras don't know yet.

Tamayo: "Very well. What about Rei's children?"

The crow smiled.