Note: This page will mostly focus of Kirito's characterization in Alicization, as he's improved well. Not his other appearances since they aren't fine. Kirigaya Kazuto (桐ヶ谷 和人, Kirigaya Kazuto?), born as Narusaka Kazuto (鳴坂 和人なるさか かずと, Narusaka Kazuto?), and known as Kirito (キリト, Kirito?) in «Sword Art Online» (SAO), «ALfheim Online» (ALO), «Gun Gale Online» (GGO), and «Project Alicization», is the primary protagonist of the main Sword Art Online series.
He had much better characterization than the previous two seasons. Rather than being an overpowered beater that only relies on dual blades, he is a very helpful guy, sometimes, dorky, uses his own smart tactics and not abuse his powers at the same time.
The idea of him bonding with his childhood friends despite having no memory of the two of them is very well executed.
Kirito learns to grow and bond with both Eugeo and Alice:
Kirito had introduced Eugeo to swordsmanship, and helped him master the Blue Rose sword.
They both have graduated into Elite disciples.
Alice is mostly seen as an older sister figure to Kirito back when they were children.
Kirito had now met Alice again after almost two decades, although both Kirito and Eugeo are petty criminals in Alice's eyes, but after talking sense to her that they only did it just because the Taboo Index was flawed, and the Administrator is evil, she now agrees to help and fight for them.
Surprisingly, he's really cute back when he was a child.
Even over the years, both Yoshitsugu Matsuoka and Bryce Papenbrook still did a great job voicing him.
Since he is less powerful than he once was, the anime gives him a chance for him to develop his own character.
After seeing Eugeo die in his arms, Kirito had already began to lose his mind and sanity, thinking that he himself does not deserve forgiveness, had emotional trauma not only losing Eugeo, but his late friends (i.e. Sachi) that died in Sword Art Online video game, but he has now changed after seeing Eugeo again one last time before waking up from his coma.
While he may still be overpowered in a few fights, he fortunately doesn't stay too powerful for long.
He accidentally sliced the arms of one of his rivals at Swordcraft Academy, Raios Antinous, when he tried to kill his friend and partner, Eugeo, since he's broken the seal of the Taboo Index in order to save Tiese and Ronye from being sexually assaulted by Raios and Humbert. This led Kirito and Eugeo to be wanted as criminals, when Raios' fluctlight collapsed, which led to his death rather than letting him live.
However, Raios did get what he deserved for his attempt to kill Eugeo and sexually assault Tiese and Ronye, both of which are truly and generally illegal.
He becomes sidelined during War of Underworld due to him being in a coma, with the main focus going to Asuna and Alice. Thankfully, he returns halfway through the season.
His voice actor Yoshitsugu Matsuoka, had also voiced Inosuke Hashibara from Demon Slayer, Sora/Riku Dola from the No Game No Life series, and Sorata Kanda from The Pet Girl of Sakurasou.
Both share the physical appearance of having black hair and black (sometimes grey) clothes.
They also share the same signature color (black).
They love to play video games, and they are very skilled at them.
They have black, blonde, and brown haired allies, as Cole has Nya, Zane (Seasons 1-3, and 7), Lloyd, Kai, and Jay while Kirito has Leafa, Eugeo, Alice, Silica, Lisbeth (real world), and Sinon (real world).
Speaking of Zane and Eugeo, they are users the elements of ice and once manipulated by their respective enemies.
They are able to wield two swords in combat (Cole with the Blades of Deliverance and Kirito with the Elucidator and the Dark Repulser/Night Sky and the Blue Rose swords).
They were once trapped in video game realities with final bosses as the main antagonists (Akihiko Kayaba/Heathcliff from "Sword Art Online" and Unagami from "Prime Empire").
They are very powerful to defeat their enemies respectively.