Webzenitsu knew tanjiro was traveling with a demon, and tells inosuke to back off;
As he is going to ask tanjiro himself;
Why he's traveling with a demon.
Webexplore and discover zenitsu’s age, height, fighting abilities, relationships, and battle experiences.
Also, you can learn about their unique personality, thunder breathing.
Webzenitsu agatsuma (我妻善逸) usually seen acting like a coward, has low esteem and sometimes gives up when given a job.
He is a demon slayer member of the demon.