In the Naruto anime, the Mangekyō Sharingan of the Uchiha clan is considered the most powerful bloodline limit. Its uniqueness is that it can continue to evolve, and each evolution significantly improves the strength of the Uchiha clan, especially the transition from the ordinary Sharingan to the Mangekyo Sharingan, which has a tremendous leap.
As we know, activating the Mangekyo Sharingan is a difficult task for the Uchiha clan, because it means facing the death of someone they cherish. Therefore, in the entire anime, there are only a few Uchiha clan members who have successfully opened the Mangekyō Sharingan, and there are even fewer people who achieve the Eternal Mangekyō Sharingan, among which Uchiha Sasuke is one of them.
Sasuke is the second son of Uchiha Fugaku, the leader of the Uchiha clan. He activated the Sharingan on the day when the Uchiha Itachi clan was exterminated. In the subsequent Sasuke War, Uchiha Itachi died, and Sasuke, who understood the truth about Uchiha Itachi, successfully opened the Mangekyo Sharingan, and his strength made a qualitative leap.
The prerequisite for unlocking the Mangekyō Sharingan is the death of a loved one. For Sasuke, there was once an opportunity to open the Mangekyō Sharingan. However, in the first battle in the Valley of the End, he gave up the opportunity to kill Naruto and activate the Mangekyou Sharingan.
The question is, if Sasuke killed Naruto at that time, would he be able to activate the Mangekyo Sharingan? Was Naruto really that important to Sasuke at that time?
To answer this question, we need to delve into the relationship between Sasuke and Naruto when they were children. Naruto has been without parents since he was a child, has no idea of the feeling of family, and longs for friends. In contrast, Sasuke's childhood was relatively intact, but after losing his loved ones, he became cold.
However, during the mission in the Land of Waves, Sasuke stepped up to protect Naruto, showing that he had already started to regard the members of Team 7 as family, with Naruto becoming his significant friend.
In the Great Ninja War, Naruto and Sasuke's tacit cooperation showed their relationship. During the final battle, Sasuke bluntly expressed how important Naruto was to him, no less than Itachi.
Therefore, if Sasuke kills Naruto during the battle in the Valley of the End, he will also immediately activate the Mangekyō Sharingan. However, he did not do this because he wanted to prove himself and surpass Uchiha Itachi. Some people may say that Sasuke has just opened the Three Tomoe Sharingan and cannot evolve into the Mangekyō Sharingan. However, didn't Obito also directly evolve from the double Tomoe to the Mangekyō Sharingan?
In your opinion, if Sasuke killed Naruto at that time, would he be able to activate the Mangekyo Sharingan?