Kyo Ethnina

Kyo Ethnina (キョウ＝エスニナ), also known as the Book Hero (本の勇者), was 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, comparable to the eyes of a dead fish. He carries a dark and gloomy aura around him.

He wears a long coat while wearing a strange belt around his chest, which is 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, its people merely NPCs that exist for his entertainment, and it shows through his frequent use of Gamer speak such as calling the waves an update.

He is 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 he refused to take in any woman whom he considers as 'used-goods', such as Albert's and Trash 2's harems. In spite of having cheated death many times the idea of a permanent death through being devoured by a Soul Eater or Soul Eating weapon terrifies him to his core.

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. Anyone who wanders inside will be lost unless he wants them to get to the mansion.

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

 * Due to him not being a genuinely chosen Hero picked out by the Vassal Book, Kyo was never able to fully use the Book's power to its maximum and in fact, the Vassal Book itself despised Kyo and called out to its fellow Vassal Weapons to have their chosen heroes kill him and free itself from his control.
 * The Vassal Book despised Kyo so much that it even went as far as creating a special case of where a Holy Weapon User was actually allowed to allow its Chosen Hero to leave weapon's native world and travel to another to kill Kyo.