Mad about what

Zenitsu knew all along, by his amazing sense of hearing, that Tanjiro was carrying a demon in his box. Zenitsu didn't know why, but the sound that Tanjiro gave off was so warm and caring that he knew that Tanjiro had good intentions, and a good reason, for carrying said demon.

True but in the episode when Nezuko comes out of her box, Zenitsu starts attacking Tanjiro for "Disobeying the Corp's rules"

not saying your wrong, you got a good point though

oh, okay.