For the man had quickly entered the Demon Slayer Headquarters, Tengen was asking around for you.

Since you two have been close friends ever since the start of his career as a demon slayer, both of you were close. Tengen was trying to find you, the Hashira needed your help with this mission.

To hunt down a demon within an town. The demon has been hunting, killing, and devouring if suited. Merely, Tengen could have handled it himself but people were suffering and sick so you were needed.