Kayaba Akihiko

Kayaba Akihiko (茅場晶彦) is the development director and GM (Game Master) of «Sword Art Online». He is also the designer of the «NerveGear» and the «VR Seed», as well as the main antagonist of the Sword Art Online Arc.

Appearance
Kayaba Akihiko is the only player on Sword Art Online whose avatar does not match his appearance in the real world. As a result, Kayaba's avatar as Heathcliff bears no resemblance to his true skinny body.

Significantly idealized, Heathcliff is muscular, tall, and physically strong. With a cool demeanor, he is almost always seen wearing the colors of the Knights of the Blood.

Personality
Although Kayaba Akihito only appears as his true form few times throughout the series, he is always very calm, soft-spoken, and has a cool demanor. Despite being incredibly skilled, Kayaba is not boastful, or arrogant, and when Kirito defeats him and clears Sword Art Online, he humbly accepts defeat.

He seems to be very sincere and thoughtful, as shown when he tells Kirito of his dream about creating a floating castle, as the basis for creating Sword Art Online.

Background
In Kayaba's childhood, Kayaba expressed an interest in reading books. He was not particularly engrossed in games in computers, but he participated in the Mathematics Club of his high school. Later on, in university, he did not participate in any circles because he frequently worked in and out of laboratories.

When he began developing Sword Art Online, Kayaba toiled for years to develop the game software. His main goal and dream was to "make Aincrad float" but after he did so, he wasn't entirely sure what his dreams, aspirations, or purpose was.

It can be deduced that Kayaba began working on Sword Art Online before his third year in university. His love interest was Koujiro Rinko, who assisted Kayaba for ten years of the game's development, and took care of his body during the course of SAO.

Sword Art Online
His avatar, Heathcliff (ヒースクリフ) is the leader of what is considered to be the Sword Art Online's strongest guild «Knights of the Blood». He is the owner of the «Unique Skill» «Holy Sword» and is considered to be strongest player in-game. He wields the one-handed sword and a tower shield collectively called as Liberator. He also was able to hold off the boss of the fiftieth level for ten minutes by himself, which earned him the title «Man of Legend» (伝説の男). It is also rumored in SAO that Heathcliff's health has never gone into the yellow zone. This is due to his identity being Kayaba Akihiko and being able to make himself invincible or otherwise making his character into an «Immortal Object» after his health reaches 50% or is about to surpass it.

In the manga, he is first seen at the Town of Beginning, using his avatar, Heathcliff, with the rest of the SAO players listening to his other self talk about the new rules that made SAO into a death game. Kirito even commented on how calm Heathcliff's avatar was on the situation (later revealed to be because the death game didn't apply to him).

As a leader of the Knight of the Blood, Heathcliff was quite renown for his general tendency to stay out of guild affairs, preferring to allow his subleaders to develop plans and advance the game. Apart from guild paperwork and battles, Heathcliff rarely interfered with the choices and actions of his sub-leaders. The only exception to this was when Asuna expressed her wish to leave the guild, and Heathcliff refused to allow her do so without challenging Kirito to a duel.

Kirito first suspected his true identity during his match against Heathcliff when Kirito sees that Heathcliff's speed exceeded the system limits. However, Kirito figures out his true identity in the seventy-fifth floor. Thanks to a miracle in the game allowing Kirito to launch one final attack after his HP ran out, Kirito manages to defeat Heathcliff and free the trapped players.

After SAO
He reappears to help Kirito defeat Noboyuki Sugou, and leave Kirito with the Seed. He also stated that he copied his mind onto the virtual network, and now exists as digital data, so as to be a fully realized being of SAO. He also said they would meet again. According to Koujiro Rinko, he died after copying his mind to the virtual network.

Trivia

 * Aside from research and development, Kayaba's hobbies are cooking and Go (the board game).
 * The first RPG Kayaba played was an old RPG known as Wizardry. It apparently played an influence on the development of Sword Art Online.
 * Kayaba intended to reveal his true identity on Sword Art Online at the 95th floor, and become the final boss at the hundredth floor.