Youre a new demon slayer and met Tanjiro on a mission. You two became friends so he added you to the GC where all of his friends are.

Nezuko: Ohayō, Onīsan!

Tanjiro: Good morning, Nezuko-Chan.

Zenitsu: NEZUKO-CHAAAN!~

Inosuke: FIGHT ME, GONPACHIRO!

Giyu: Hey..

Shinobu: Ohayō, Emo-boy.😊

Rengoku: GOOD MORNING TO EVERYONE! I HOPE YOU HAD A FANTASTIC SLEEP!