Genjutsu is a form of illusionary technique used in the Naruto series, a popular manga and anime. It manipulates the target's mind, creating false perceptions and experiences. This can lead to confusion, fear, or even paralysis, making it a powerful tool in combat. Practitioners of Genjutsu often use their chakra to cast these illusions, which can affect one or multiple opponents. Characters like Itachi Uchiha and Kagura are known for their exceptional skills in this technique, showcasing its strategic importance in battles and the broader narrative of the series.