Accel World - Some Volume 12 spoilers

-The White King is KYH's older sister. Her avatar name is "White Cosmos".
-She tricked KYH into killing Red Rider, and KYH in turn tried to PK her in real life wwwww (this was hinted in vol10), which is the reason why KYH got exiled from home ("to reat her mental illness") and only a lawyer came to see her even when a car ran her over. WC did get injured. Oh yeah, she's also confirmed KYH's "parent".
-Crow got a new ability called Optical Conduction
-Lime Bell's new nickname is Watch Witch (kinda like how Raker is called ICBM sometimes). She dived into the unlimited stage and got an ability called Acoustic Summon that can gather Enemies (ability's from an item called Choir Chime).
-Aqua Current appear once again when Crow was attacked by Argon Array.
-More on Graphite Edge, he likes to give other nicknames and act totally like a kid (doesn't sound like Kirito at all tbh). He didn't have enough safe points so he decided not to get to level 9 before the other Kings. His swords are made of Hyper Diamond (hardest material in AW), can completely reflect one full on assault from KYH; extremely versatile with his swordsmanship in that he can use them to defend and attack. Since he only upgraded his swords, his body's super weak (so weak that he would lose to Ardor Maiden in close combat without 'em, and AM's already super weak close range).
-Red Rider, has an equipment called Arms Creation, and is also called Master Gunsmith (according to Kawahara's livecast for that episode, his battle avatar's totally a cowboy image with the horse if you missed that tiny detail). His creation has a symbol of crossed guns which acts as a safety switch, which Rider can control at will.
-Blood Leopard's special attack is called Vital Bite, which absorbs HP and also Mental Bite, which absorbs special attack gauge.
-Green Grandee has an ability called Double Payback, which is exactly like it sounds (2x reflect damage on enemy attack).
-Blue Knight has abilities called Pain Killer and Limit Surpass.
-White Cosmos is also nicknamed Transient Eternity, has 0 offensive abilities, but her IS ability makes her totally invisible, after she reached level 9, nobody can see her but other kings and her own legion. Ivory Tower also has the ability call Under Cover.
-Wolfram Cerberus has 3 personalities (like name suggested). Middle head wants to collect burst points only; left head has ability call Wolf Down that can copy any ability, right now he wants The Disaster.
-Magenta Scisscor is from Setagaya and is the first Burst Linker to install the ISS chip, but is not part of the Accel Research Committee.
-ISS chip before installation is black and has Red Rider's symbol on it.

===============================================================================================

The white kings is KYH one year older sister.She doesn't possess any natural attack power, and she doesn't appear in front of anybody besides her legions top lieutenants. KYH mentions she used to fight in the very beggining of Brain Burst (implying she is an originator), but that she used something, either an ability or a enhanced armament, that made he enveloped with light so the opponent couldn't see her form (essentialy confirming she is the person with Black Vise in the Chrome disaster backstory).

================================================================================================

Looks like there is some confusion about that. What actually happened was that the white king approached KYH and showed her a gun made by Red Rider, claiming that one of it would be given to every legion, would only be usable when your legion is attacked, and never missed, had infinite ammo and devastating power. She made a demostration of the power of the gun, and said it was to be a deterrent that would make it impossible to attack another legion, as the defending side would always win, essentially enforcing the truce regardless of the other kings opinions.

KYH kills him with the intention of stopping the making of the other guns. However, after the destruction of NN, while she was already in hiding, she notices that, when she killed Rider, one of the guns was transferred to her inventory, as sometimes happens when you kill someone. The weapon in unlocked, but it won't fire. She realized he made it that way as a symbol of peace. She runs to her sister's room to accuse her, to which she only agrees to everything, smilling. Hime tries to force her into a duel with a box cutter, but her sister tells her not to do that, as she doesn't want to take even brain burst away from her. Hime, realizing she could never win, ends up stabbing her in the hand, and that's how she was throw out of the house.