|“||"Are you all so threatened by these little monsters? It seems there is but one true hero among you."||”|
—Glass, Volume 3, Chapter 12
Glass is a beautiful young woman with long black hair trimmed and styled after a traditional Japanese Princess (姫 Hime?) haircut. She wears a jet black kimono with silver embroidery like those worn during a funeral. She has pale skin that is slightly translucent due to her racial characteristics as a Spiritual Being.
Glass comes off as stern, cold, and serious. Glass holds strong loyalty when it comes to her world, she also takes pride in being a Vassal Wielder and Hero and has high expectations towards other heroes, friends, or foe, from her world or not.
Because of her strong loyalty to her world, she was willing to even kill the Four Legendary Heroes of another world to save her own.
She is serious in her mission and doesn't like laying back of her friends. Later in the series, her serious expression is changed when she is around Kizuna to a more friendly and joyful expression. Naofumi considered it weird for someone who always has a calm and cool expression to have such expressions.
Glass comes from a race of Spirit People. The disciple of the famous martial art school was in the ceremony to decide who would hold the responsibility as the Vassal Fan holder. The chosen person has to fight the Demon Dragon Emperor that ravaged the people of her home country.
Initially, Glass was denied to participate in the ceremony because of her birth (The reason for her being discriminated that day was not touched, as Kizuna felt it to be Glass' personal and avoided that topic), however, she was chosen after all the disciples of the school were turned down by the weapon. The disciples were bitter about Glass being chosen over them, so they got together and cut ties with her and asked her not to come back. The disciples thought that Glass would die in the task and hoped that they would be chosen next to wield the vassal weapon. They fought among themselves.
Kizuna was summoned as one of the legendary heroes of her world in the neighboring country and aided Glass on her adventure, as she was summoned for the same task as Glass. Together, they fought and defeated the Demon Dragon Emperor. Later, they became very close friends and Glass moved to the country which summoned Kizuna and lived there.
After numerous events, Kizuna was trapped in an inescapable labyrinth. Glass' world was on the verge of being destroyed because of the absence of one cardinal hero and the ignorance of the other cardinal heroes.
Not knowing any other way to save her world, she came to know of the research of the ancient text by L'Arc's country which depicts the waves to be a phenomena of merging of two or more worlds and also added that to extend the life of her world, the vassal weapon wielders must kill the cardinal heroes of the world which is on the other side of the wave, to ensure their destruction and prolong the life of this world. Glass and her comrades took it upon themselves to travel to Naofumi's summoned world to kill its legendary heroes.
- Glass is the only named character from her world who appeared in the original Web Novel.