Concentration
Concentration is a character’s ability to focus their mental abilities on a task. In the use of Genjutsu, this means that a character can focus on the task of the mind, which is important and key to that kind of chakra manipulation. It also means that a character is able to realize that an enemy is trying to manipulate their own mind and give them a chance to defend against it. For those who do not practice the art of illusions however, concentration means a keen eye for detail and weaknesses. Taijutsu users with enough concentration can find weaknesses in the enemy, allowing them to exploit them at will like chinks in armor. As well, those who manipulate Ninjutsu are able to focus their energy more efficiently, cutting down on wasted chakra.