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 homegrown 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' 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 tortoise so that they would be able to beat it the same way twice.

Volume 7
Kyo made his base of operations around the Spirit Tortoise's magical core where he had plugged in the three heroes to serve as power sources and set to work using the Spirit Tortoise's flesh in his own experiments in minion manufacturing and army them with Legendary Sword, Spear and Bow replica's using the Spirit Tortoise's mimic familiars as a base. 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 worlders 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 using a barrier to protect himself Kyo cuts his losses and destroys the Spirit Tortoise's core taking all of the energy inside for himself, then he covers a retreat back to his world with the Spirit Tortoise'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 of 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 about them he attacked his ostentatious ally Albert, killing him, hijacking his humunculi and used that to forcibly learn his reinforcement method for his Vassal Mirror 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 of the situation 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.

Volume 9
Kyo sent the women on a terrorist attack into the heart of Kizuna's territory, joined by Yomogi armed with a replica legendary sword, where they attempted to plant an accessory on their hourglass that would allow him to send his army through. When the women failed to plant a device on the hourglass that would allow him to take it over, Kyo detonated the weapon replica's he gave them to take out their forces.

Naofumi responded by feeding the replica to his shield and nullifying the explosion. Not only had Kyo failed but with the help of Yomogi, who has been half convinced of Kyo's guilt, Naofumi's group was now on their way into Kyo's Territory. Kyo did have the foresight of cutting off Yomogi's specialized accessory for finding her way back to his base and changing the locks in his mansion but his fog was nothing that Raphtalia couldn't guide the group through.

He also seemed to progress his experiments in human sacred beast hybrids, Trash 2's sacred beast clones, and Albert's humonculi with the rest of the members of Trash 2's and Albert's harems completely mutated into monsters. Naofumi and company's response is to tear through his monsters and his mansion and all the traps therein making their way to his underground laboratory.

There Kyo finally reveals his true colors: that he is little more than a psychopath one who sees the world as a game, it's waves as periodic updates and it's people as NPC's all of which exists for his own amusement. With no doubt left to the true nature of Kyo, every unleashes their skills and magics on his head. Kyo neuters their attacks by making use of the Spirit Tortoise's energy to increase the gravity of the area.

Naofumi responds using the magic bullet counter of his newly unlocked Demon Dragon Shield to destroy the mandala Kyo was using to maintain his gravity magic and Chain Shield to tie up his minions allowing the others to wipe out the humonculi. Kyo counters with a skill that turns their magic against themselves though the group barely keeps up with the use of Magic Water and Rishia's naturally low stats allow her to ignore the effects of the skill.

Rishia seizes the opportunity and finally frees the Vassal mirror from the half-dead Albert. Kizuna and Naofumi, on the other hand, apply their attack support skills to Kyo in time for Rishia to land a hit on him severely damaging him in the process. Naofumi follows up with the upgrade spirit tortoise magic core shield to drain magic off of his attacks. Cornered Kyo is forced to use his last resort: he triggers a wave which teleports, Kizuna, Glass, L'Arc, and Therise away and gives him an opening to steal the Spirit Tortoise power Naofumi already collected.

Unfortunately for Kyo, his actions end up hoisting himself by his own Petard, the Wave allowing Naofumi's group to regain and reacquire the stats they had on the previous world and stack them with the ones from this one. Not done yet Kyo summons the Spirit Tortoise minions armed with legendary weapon replica's in order to kill them, Rishia, however, has been dramatically empowered thanks to the combined levels and slaughter's the neo-guardians.

Getting desperate Kyo imbues himself with more Spirit Tortoise Energy and summons his Library, an alternate dimension filled with books that he uses to continuously pelt the group with attacks. Using illusion magic the group distracts Kyo and Naofumi switches to the wrath shield to burn the whole place to the ground. The others support Naofumi by draining some of the curse through Filo while he protects them with shield prison while Naofumi turns the library into ash.

High on Naofumi's battle rage, the group unleashes their attacks on Kyo, who attempts to trap and kill them with another prison type skill before Naofumi defends them again. The group's repeated use of defense raiding attacks to shatter Kyo's defenses as he attempts to charge up an attack based on the Spirit Tortoise's lightning. Naofumi attempts to use Dragon Pulse to counteract the effects of Kyo's attacks he is contacted by a voice from within the shield.

Stating that it would be inconvenient to let him die the voice agrees to assist Naofumi in casting his spell leading to the use of All Sacrifice Aura on himself, Filo and Raphtalia who then use their vastly empowered stats to savage the reincarnator mercilessly finishing him off with Iron Maiden. Kyo suddenly unlocks his own version of the curse series, both attacking Naofumi's group and trying to heal his own wounds.

Naofumi switches to the Spirit Tortoise shield to gather the energy scattering off of Kyo, the Mirror Vassal weapon flies over to offer Naofumi additional support allowing him to land a massive blow against Kyo who is finally put on the verge of death before Rishia kills. However Kyo is not finished yet, his soul excised from his corpse and on it's way to moving into a new body imbued with Spirit Tortoise energy.

Unfortunately for him, Raph Chan is able to see him in his soul form leading to Rishia chucking an Ofuda with Soul Eaters inside at the soul and the monster finally causes Kyo breathes his last. Naofumi takes the rest of the Spirit Tortoise energy back, destroys all of his research and equipment, before finally using the Spirit Tortoise shield leads the group back to their proper world.

Relationships

 * Vassal Weapon Holders
 * Rishia Ivyred: 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.

Trivia
Information to be added later.