Sword Art Online: Alicization has returned with the second half of its third season, and it's the start of the intense War of Underworld arc. Although the third season initially began with Kirito already in a dire situation with his physical body being kept in a near vegetative state, his mind was still being kept brimming with energy due to a recent experiment allowing him to jump into a new virtual world. But now his condition has gotten even worse following the battle with Administrator as he's no longer got the same mental faculties as he did before.
It's revealed that following the battle with Administrator, and following his failed connection back to the real world, Kirito has been left without emotions and his ability to speak. Meaning now Alice has to try her best to protect him as they're still being branded as criminal traitors by the Imperial Knights.
Before Season 3 went on hiatus, Kirito connected to the real world for a brief moment and nearly re-connected with Asuna. But something went wrong as at the same time, Rath was being raided by mercenaries. This resulted in some kind of explosion, which reduced Kirito to this new state (and still without his right arm). Although this seems like a coma, Kirito has maintained his motor functions and is responsive to things.
He still eats when being fed, and it seems like he can hear Alice speaking to him, but something else is clearly wrong. Kirito starts to rile up when he's separated from his and Eugeo's swords, and he's constantly reaching out to something that no one else can see. But until Alice can get to the root of why Kirito is like this, or until he snaps himself out of it, she's going to be alone facing all new dangers.
If you wanted to jump back into the series, you can currently find Sword Art Online: Alicization - War of Underworld streaming on Crunchyroll, Funimation, HIDIVE, and Hulu. War of Underworld is described as such, "Kirito, Eugeo, and Alice. Six months have passed since the two disciples and an Integrity Knight brought down the pontifex, Administrator. With the fighting over, Alice has been living in her hometown of Rulid Village. Beside her is Kirito, who has not only lost his arm and soul, but also his dear friend.
As Alice devotes herself to looking after Kirito, she too has lost the will to fight she once had as a knight. "Tell me, Kirito… What should I do?" Nevertheless, the time for the final stress test – one which will engulf the entire Underworld with tragedy – draws relentlessly closer. Meanwhile, in the deepest areas of the Dark Territory, the Dark God Vecta has resurrected, as if to have waited for this very moment. Leading an army of dark forces, they begin their invasion into the human empire in hopes of attaining the Priestess of Light.
The human empire force led by the Integrity Knight Bercouli prepares for a war of an unimaginable scale against the army of the Dark Territory. Even then, Alice is nowhere to be seen, nor the two heroes that saved the realm… The curtain rises on the final chapter of the SAO series' longest and most glorious battle – the Alicization arc."