There are few characters in the Naruto series as tragic as Itachi Uchiha. In a world where the way of the ninja reigns supreme and people compete to be the strongest shinobi, Itachi was literally one of the strongest ninjas in history. As he was a prodigal member of the prestigious Uchiha Clan, his skills were practically unmatched. This made him a formidable foe when he joined the infamous Akatsuki gang. But in the last moments of his life, he died with a smile on his face. What caused that bittersweet moment?
Even as a young man, Itachi found himself working as an assassin for the Hidden Leaf Village. He was tasked with spying on his clanmates and reporting on his insurrection plans. At the height of the tension, Itachi was forced to kill his entire clan. He managed to save his brother Sasuke, who was unaware of the truth of his actions. Itachi tearfully exiled himself from the Hidden Leaf to cover up the conspiracy.
Years later, they would meet in one more clash.
Source: Crunchyroll Why does Itachi Uchiha smile when he dies? He has to do with Sasuke.
Itachi and Sasuke were initially close as brothers, with Itachi often taunting his younger brother and punching him in the forehead while hiding dark truths from him. After Itachi killed his fellow Uchiha, Sasuke swore to avenge his clan by killing Itachi. Sasuke goes to great lengths to gain enough strength to defeat his monstrously powerful brother, even going so far as to defect from the Hidden Leaf Village and betray Naruto Uzumaki.
After years of training, Sasuke was ready to fight Itachi.
Despite Itachi’s considerable abilities, he is rapidly approaching his limit as he and Sasuke begin their final fight. His mastery of the Mangekyō Sharingan would soon drive Itachi to blindness, and the only way to prevent it was to steal his brother’s eyes.
This puts them on even ground as the two exchange blows using their respective ninjutsu mastery. Itachi eventually gains the upper hand, but only after expending an immense amount of chakra.
In his final moments, Itachi appears to be reaching out to gouge out Sasuke’s eyes. Instead, he playfully punches him in the forehead like he did so often in his childhood. He then dies with a smile on his face, with Sasuke having fulfilled his now hollow revenge on him.
Sasuke later learns the truth about Itachi’s actions from Madara Uchiha, and finds out how the Hidden Leaf Village forced Itachi to murder the Uchiha against his will.
Itachi’s will to keep the peace in the Hidden Leaf Village can only be rivaled by his love for his little brother. He knew that this act of betrayal would mark him for life and, in his own way, he encouraged Sasuke to become strong enough to survive the cruelty of his society and the dangers of being a ninja. By defeating his older brother, Itachi knew that Sasuke would be fine, having given him a reason to become so strong. Who wouldn’t smile after seeing how big his little brother had grown?
Itachi’s greatest hope was that Sasuke would eventually use this power to break free from the shackles of revenge, become a better ninja than him, and not swear revenge on the Hidden Leaf Village.
Sasuke would immediately go on to swear revenge in the Hidden Leaf Village.