Board Thread:Theories and Speculation/@comment-36512555-20200202084241/@comment-9782468-20200203161151

I think it depends on the type used. In all honesty Kishi left Genjutsu very underdeveloped compared to the other ninja categories.

For the most part, I think you're right. A Chunin theoretically could catch Hashirama in a Genjutsu, which he'd most likely break with ease.

But there's Genjutsu for immobilizing and Genjutsu for deceiving. The deceiving type Genjutsu, though harder to use (apparently), is harder to detect when done right, and therefore the victim may not even know to try to break out. Like how Danzo never tried to break Sasuke's Genjutsu on him, because it was so subtle that he didn't realize it was Genjutsu.

So while I think Genjutsu immunity doesn't exist, the higher you attention to detail, the higher chances of you knowing you're in a Genjutsu and therefore breaking out. That's why the Sharingan is so potent against Genjutsu; they take in every detail, and they can also see chakra. It makes it so making Genjutsu believable to Sharingan users is extremely difficult