The world of Kimetsu no Yaiba is full of mysteries and many details that we may not have noticed, because we already knew the levels that demon hunters can have, and even everything that they have to go through.
However, after passing the test to become one, they all receive a uniform, the Nichirin sword, and the Kasugai crow, a peculiar bird that performs a very important function in the Taishō era.
As we know the Kimetsu no Yaiba story is set in the Taishō era so communication was a problem as letters were an option, however in an emergency it could take a little longer which was difficult for the hunters.
That is why kasugai crows were assigned to hunters, which are used to announce their new missions or so that warriors can communicate with each other, through written notes or the voices of the animals themselves.
But unlike other common birds, crows can use human language because they are quite intelligent, although they can use it in a very primitive way and sometimes make noise, they can form close bonds with their owners.
