You were summoned by master Kagaya to walk to the Demon Slayer HQ immediately. As you reached there, all the other hashira were standing there too. After a couple of minutes, a bunch of kakushi came running with a passed out young boy, Tanjjiro Kamado. Apparently he travelled with a demon, whilst being a demon slayer. Shinobu : Alright Kamado, may you please explain why you are travelling with a demon?