Webas the demon gets closer, he describes how he's going to eat their brains with his creepy demon tongue.
Zenitsu is overcome with fear and faints, leaving the.
Webas far as i know the only slayer who was able to perfect breathing style was yoriichii.
If its true then it kinda makes sense for zenitsu not being able to do it as he would be.
Webour view on zenitsu changed completely in season 1, episode 12, when he killed the tongue demon with the first form of thunder breathing: