Kyo Ethnina

Kyo Ethnina (キョウ＝エスニナ), also known as the Book Hero (本の勇者), is one of the Vassal Wielders from Glass' World.

Appearance
Kyo has white hair with a silvery sheen. His eyes are described as stagnant and rotten, comparing them to the eyes of a dead fish. There is an air around him that is dark and gloomy.

He wears a long coat while wearing a strange belt around his chest, which are full of test tubes, he also wears leather gloves and shoes. He is described looking either like a scientist or an alchemist.

After his death, the remnant of his soul takes the appearance of a skinny man in his thirties, completely different from his physical appearance, but his voice is the same.

Personality
Kyo fancies himself a genius. A rampant egomaniac, whenever his opponents make mistakes, he will repeatedly call them stupid, yet he makes use of his attacks in extremely simple and easy-to-see-through ways. He sees the world as nothing more than a game, it's people merely NPC's that exist for his entertainment and it shows through his oft use of Gamer speak such as calling the waves an update.

He's also a rampant pervert, as shown by his openly admitting that he intended to brainwash the members of Naofumi's party and add them to his harem of other brainwashed women, but refused to take in any woman whom he considers used goods, such as Albert's and Trash 2's harems. In spite of having cheated death many times the ideal of a permanent death through being devoured by a Soul Eater or Soul Eating weapon terrifies him to his core.

Abilities
He was a genius, able to study, control and go around many phenomena, including the summoning of an artificial Wave of Catastrophe, control Spirit Tortoise's power, etc.

He held the Vassal Book against its will and was well versed in using its power. However, since his vassal weapon opposes him, he wasn't able to use all of his powers and even after implementing many more power up methods than the other heroes, the true chosen heroes were still able to fight against him.

Most dangerous among his abilities though is his status as a Reincarnated individual. Whenever he dies his soul is able to wander free of his body to take on a new one, often times the home grown humonculi that he has made and modified specifically for the purpose of housing his soul and improving on his original.

Background
Some time ago, Kyo died in his old world, but through circumstances unknown to his enemies he was reincarnated into Glass's world. He was mentioned to have traveled around the world, asking people about their troubles and invent a way to solve them. He saves Yomogi along the way.

Long ago, he built his laboratory inside a sealed mansion far away from the capital. It was within a thick fog that anyone wanders inside will be lost unless he wants them to find a way.

Volume 6
Kyo infiltrated the world specifically for the purpose of using it as resources for increasing his own power. He awoke and took control of the Spirit Tortoise and sent it on a rampage for the purpose of harvesting the energy of the world. When Motoyasu Kitamura, Ren Amaki, and Itsuki Kawasumi tried and failed to stop it he captured the three of them and forcibly connected them into the tortoise to serve as another power source for the Guardian Beast.

Initially concerned when the Tortoise was decapitated by Naofumi Iwatani's party after he and the allied forces left he simply modified the turtle so that they would be able to beat it the same way twice.

Volume 7
Kyo made his base of operations around the Spirit Turtle's magical core where he had plugged in the three heroes to serve as power sources and set to work using the spirit turtle's flesh in his own experiments in minion manufacturing. After Naofumi and his party fought their way to the core a battle broke out between Kyo's and Naofumi's groups, in particular Rishia Ivyred, thoroughly enraged by Itsuki's mistreatment, ended up clashing with Kyo.

Naofumi's group was joined by three of Kyo's fellow other worlder's Glass, L'Arc Berg and Therese Alexanderite and with Ost Hourai's help Naofumi is able to cast All Liberation Aura on his allies dramatically boosting their fighting power to counter Kyo's use of gravity magic. While ssing a barrier to protect himself Kyo cuts his losses and destroys the Spirit Turtle's core taking all of the energy inside for himself, then he covers a retreat back to his world with the Spirit Turtle's energy in tow, leading to Naofumi's party and the three other worlders to follow him.

Volume 8
Before Kyo arrived back in his world Kyo divided Naofumi's Party separating him from Raphtalia and Filo and dumping him and Rishia into The Labyrinth. Sadly for Kyo not only did Naofumi reassemble his party but he had also saved Kizuna Kazayama from the labyrinth but Raphtalia had since become the wielder of the Vassal Katana. Still Kyo had taken advantage where he could, for starters by spying on Raphtalia's group he was able to learn all of the weapon reinforcement methods Glass's group knew.

More importantly than that once he learned them he attacked his ostentatious ally Albert, killing him, hijacking his humonculi and used that to forcibly learn his reinforcement for his Vassal Mirror method as well. However he was unable to make use of their full power, to be more accurate his enslaved weapon refused to let him use them. Still Kyo took advantage adding the resources of Albert and Trash 2 to his own and recruiting their harems as experimental subjects, grafting guardian beast flesh onto their bodies and equipping them with Legendary weapon replicas he made.

The women were sent on a terrorist attack into the heart of Kizuna's territory where they attempted to plant a accessory on their hourglass that would allow him to send his army through, and when that failed attempted to detonate the weapon replica's he gave them to take out their forces. However not only had he failed but with the help of Yomogi Naofumi's group was now on their way into Kyo's Territory.

Relationships
Rishia considers Kyo to be the person she could never forgive and believes that there was a destiny than it was hers to kill Kyo. Rishia unlocks her hidden potential to fight Kyo which made Naofumi nickname her as a protagonist. Kyo was also easily annoyed by Rishia for her ideals and also for getting on his way. She always managed to spoil his plans on many occasions.
 * Vassal Weapon Holders
 * Rishia Ivyred