Board Thread:Rebirth: Applications/@comment-24384232-20140930010546/@comment-13970942-20140930112928

This would be because of how nenjutsu and genjust operate. Genjutsu modifies or deceives the perceptions of those it influences, whereas nenjutsu characterizes a mastery of one's own perceptions. A nenjutsu practitioner often has a host of various senses available to him beyond the scope of a genjutsu user's ability to imitate. A genjutsu can't reasonably trick senses caster himself doesn't possess. For example, he couldn't create the illusion of ultraviolet color if he can't perceive it. He couldn't likewise create the illusion of sound beyond human hearing, unless he's experienced it himself. If a character that's mastered nenjutsu is employing multiple such non-human senses in tandem, it becomes nearly impossible to use elaborate genjutsu on him without revealing your hand; the various inconsistencies between your genjutsu and his other senses would reveal the deception. Isolating and eliminating the interference of the genjutsu then becomes trivially simple, once it's been identified. Nenjutsu really is a legitimate foil to any form of genjutsu. It's the mind's immune response to genjutsu's disease.