One of the four 'Coffin Knights' The four knights released from the coffins that Pazuzu attempted to keep hidden throughout Aegis of Uruk. Without Pazuzu, they have awakened and now roam the Tower without a master, attacking various climbers as they see fit. Gremica reveals that they are magical machines, created from the Dark Armour formerly used by the Sumar Empire (Red Knight, Blue Knight, Mirror Knight, and Hyper Knight) and their individual characteristics likely carried over. Henaro's motivation for climbing the tower is to recover the four knights by the orders of Amina and protect the king's shadow. (Source: Wikipedia)
Suguha is Kazuto's adoptive sister in the real world, although later revealed to be his cousin. She is an accomplished kendo practitioner, having practiced for 8 years, following her grandfather's wishes. In ALO her avatar name is Leafa. Suguha originally disliked VRMMO games for it hid peoples' nature and reality, as it did with Kazuto. She took up ALO in order to understand Kazuto better when he was trapped in SAO. She won the Sylph tournament, earning the title as the strongest Sylph before the events of the Fairy Dance Arc. She learned how to play ALO from her classmate, Nagata Shinichi. Suguha has become very good at ALO, because of the many years she has practiced kendo and the skills learned there were very effective for fights in ALO. She enjoys flying in the game so much that Recon even nicknamed her as "Speed Holic."
A beta tester that appears in the third story of Volume 8. He teams up with Kirito to complete a quest.
One of founders of Rulid Village, as well as the Knight Leader of the Integrity Knights, and the oldest Integrity Knight in existence. Bercouli's weapon of choice is the Time Piercing Sword.
A friendly player that meets Kirito at the start of the game and quickly befriends and learns from him. He and Kirito later separate because he has friends who were also new to the game so he couldn't leave them. He survives for the past two years and managed to protect his friends the whole time, something Kirito regretted not doing. He is a katana user and the leader of the small guild Fuurinkazan who participates in the boss battles. As one of the few people close to Kirito, he always keeps him in check and wants Kirito to survive the game. He chose the Salamader race in Alfheim Online. In the side story Caliber, he fell in love at first sight with the girl on the cage named Freyja and agreed that he will help her find her tribe's treasure which is a hammer, though the decision still remains to be a team's decision. The team said yes on Caliber and it turned out that the girl they saved was Thor. It was revealed that Thor disguised as a beautiful girl to get close to Giant King Þrym and retrieve his hammer. Thor defeated Giant King Þrym and that stopped the medallion from being corrupted and ending the quest.
She is 13 years old and a middle level dagger user. She is a very cheerful and sweet girl. She is one of the very rare "Beast Tamers" in SAO. She has a very rare familiar a "feathery dragon" that she named Pina after her cat in the real world. She treasured Pina a lot and was the reason she survived in the game. Aside from being a female player, she is also a Beast Tamer and thus perceived as an idol amongst the middle level players. She received endless invitations from parties and guilds who wanted an idol player to join them to get more fame. Because of the attention she got, she became overly proud of herself and left a party one time after a misunderstanding. She got surrounded by monsters and lost Pina in the end. She was then rescued by Kirito who was passing by and helped her to resurrect the dead familiar. Kirito then revealed after getting the revival item that he got close to Silica because she was targeted by the orange guild, Titan Hand. He received a request from a player to have this guild be put to prison after getting ambushed and his comrades got killed. After showing superiority in level, they surrendered and were sent to prison. She wanted to join Kirito in the front-lines but they had a huge level gap and she will not survive there. Kirito assured her that levels don't mean a thing as they are already friends. When she transferred her game account to ALFheim online she brought Pina with her. In ALFheim Online she chooses the Cait Sith race. After the SAO incident she is shown to go to school with Lisbeth, Asuna and Kirito and along with Lizbet makes a "pact" to allow Kirito and Asuna to have one month together without interference before they attempt their individual moves on Kirito due to their feelings for him.