The Mangekyo Sharingan is a highly coveted ocular ability in the Naruto series, known for its immense power and significant impact on the plot. Despite its near invincibility, Naruto introduces a debilitating drawback to balance out its overwhelming strength - the gradual loss of vision. Each use of this technique chips away at the Mangekyo's luminosity, eventually rendering its user blind after prolonged use.
Interestingly, some Mangekyo users such as Itachi and Sasuke have succumbed to blindness, while others like Obito and Kakashi seemingly did not experience this side effect. Although Obito's case is unique due to the infusion of Hashirama's cells into half his body, it is unclear why Kakashi did not undergo any visual impairment despite possessing the Mangekyo for almost two decades. However, Kakashi has mentioned experiencing unclear vision during the Fourth Great Ninja War, which raises questions about the true effects of the Mangekyo Sharingan.
Kakashi's Unique Mangekyo Sharingan
Possessing a Sharingan as a non-Uchiha is a rarity, and Kakashi's body was ill-equipped to handle the strain of this powerful ocular jutsu. His Sharingan remained active at all times, resulting in a significant drain on his chakra that would leave him bedridden for days after just one use. Despite the difficulties, Kakashi managed to utilize the Sharingan and its advanced Mangekyo version several times throughout the series.
While the base Sharingan did not affect his eyesight, the Mangekyo had the potential to leave a lasting impact. However, Kakashi had never mentioned any weakening of his eyesight until the Great War arc. The only Mangekyo ability he used was Kamui, which was less taxing than other abilities like Susanoo and Amaterasu. Despite using Kamui multiple times throughout Shippuden, Kakashi never experienced any blinding effects aside from the intense chakra drain.
Kakashi's Mangekyo Usage Was Minimal
It is unclear why Kakashi only experienced the drawbacks of Mangekyo during his fight with Madara Uchiha, despite having used it multiple times before. Some theories suggest that the severity of the drawbacks may increase with prolonged usage or that the emotional toll of the fight may have triggered the negative effects. Another possibility is that Kakashi had been suppressing the drawbacks with his Sharingan's ability to copy other jutsu, but was unable to do so during his fight with Madara. Regardless of the explanation, it remains a curious inconsistency in Kakashi's use of the Mangekyo Sharingan.
Although Kakashi made significant use of his Mangekyo, he was still overshadowed by Itachi, Sasuke, and Madara. The three Uchihas frequently utilized their Mangekyo Sharingan, employing techniques like Susanoo and Amaterasu in almost every battle. However, their vision deteriorated over time. Itachi, who had his Mangekyo for several years, experienced particularly rapid degradation. Sasuke and Madara also suffered vision loss early on, which could be attributed to their consecutive battles.
Kakashi's Mangekyo was introduced relatively late in the series, making his usage of it much more limited compared to other characters. He struggled to master the technique, resulting in exhaustion and debilitation after each use. As a result, he rarely utilized his Mangekyo and only did so in mass during the Fourth Great Ninja War, which unfortunately caused him to experience blurry vision for the first time.
Kamui Is a Low-Impact Mangekyo Ability
The destructive abilities of the Mangekyo are highly classified, with varying impacts on the wielder's vision. The Susanoo appears to have the highest impact, as evidenced by Sasuke's considerable pain while manifesting a full-armored Susanoo. Conversely, Kamui seems to have the lowest impact, as both Obito and Kakashi have consistently used it without experiencing any excruciating pain or bleeding eyes.
Although Kakashi appeared to suffer from intense strain after using Kamui, it's important to note that he generally has a low tolerance to Mangekyo strain. Even the base Sharingan triggers a similar response in him, making it understandable that he would experience significant stress while utilizing the Mangekyo's abilities. Despite this, Kakashi was still able to use Kamui multiple times in succession during the war, indicating that it is not a high-intensity ability and won't necessarily lead to blindness. Based on these events, it can be concluded that Kamui has a low impact on Kakashi's vision and is a relatively safe ability to use.