8 Dark Facts About the Sharingan, Having a Dark Secret Behind the Power of the Uchiha Clan

Unlike other dojutsu, the Sharingan cannot be activated just like that. This eye only appears when the user experiences deep emotional trauma, often involving death or suffering. The activation of the Sharingan stems from a strong sense of loss, amplifying the dark nature of its power.

To achieve a higher form of the Sharingan, known as the Mangekyō Sharingan, the user must experience the death of someone they deeply love or even kill them themselves. This is the dark price that must be paid to gain greater power.  

The excessive use of Mangekyō Sharingan will gradually make its user blind. This side effect emphasizes that great power comes with great risk, and users must sacrifice their vision for greater strength.

To avoid blindness, a Mangekyō Sharingan user must steal the Mangekyō eyes from their siblings, an act that signifies betrayal and violence within the family. This is the only way to obtain Eternal Mangekyō Sharingan that does not cause blindness.

As the power of Sharingan increases, its users are often tempted by dark power and ambition. A prime example is Sasuke, who after obtaining Mangekyō Sharingan, became obsessed with power and revenge, straying from the moral values he once held.

The ability of Sharingan to control Bijuu (tailed beasts) is one of its darkest aspects. Madara Uchiha used Sharingan to control Kyuubi (Nine Tails) and destroy the village of Konoha. Its power to manipulate such strong creatures makes Sharingan very dangerous.

Kotoamatsukami, one of the genjutsu techniques from Mangekyō Sharingan, allows its user to control the thoughts of others without them realizing it. This is the most subtle and dangerous form of mind manipulation, as the victim never realizes that they are being controlled.

One of the strongest Mangekyō Sharingan genjutsu, Tsukuyomi, is used by Itachi Uchiha to mentally torture his enemies. The user can create a world where they have complete control over time and space, causing the victim to experience suffering for days in just a few seconds in the real world.