Chi

Kai (カイ) (Χι) is a member of Shadow Garden, being one of the Named Number ranks. She primarily works as a direct subordinate of Epsilon.

Appearance
Kai is an elf with short blonde hair and emerald green eyes with an athletic build and a modest chest. Her right eye is blind and has an eyepatch which is hidden by her bangs. She sometimes decides to dress more in men's clothes, since according to her, it helps her to collect information in different details, other than what she likes as woman.

As a member of Shadow Garden, she wears a dark slime bodysuit, stylized with gold decorations, a short shoulder cape, and a jacket. The design of her suit is near identical to Omega's, but her counterpart doesn't have a shoulder cape.

Personality
Little is known of Kai's past or personality, other than she was abandoned like the others in Shadow Garden when stricken with Demon Possession and became loyal to their cause of destroying the Cult of Diablos.

While active on Shadow Garden missions, Kai is steadfast in her duties, executing her objectives to their fullest. When Kai is in her civilian dressing, she is seen to be friendly toward citizens and her coworkers, Omega especially as the two are partners and direct subordinates to Epsilon.

Web Novel
Kai is a quiet person, she only responds to orders from her superiors with short sentences or only responds with nods. She behaved like that not because she was disobedient to her superiors, but because she was a social phobic person.

She has great anxiety and fear when interacting with other people. This was proven when he was ordered directly by Shadow, Kai responded with her body shaking in fear. However, Shadow immediately overcomes this by having a relaxed conversation containing advice for her.

Background
Like the other girls descended from the heroes, Kai had contracted demonic possession and was discarded and abandoned by society until she was forgotten. She was found and rescued by members of Shadow Garden sleeping alone in a trash at the end of the alley, malnourished with the curse spreading over her body. Shadow Garden cured her, elaborating the truth, earning her loyalty and subsequently recruited her into the organization, being among the earliest recruited when Shadow Garden began their membership expansion.

At some point later, she rose through the ranks to become one of Shadow Garden's double-digit Numbers because her ability and strength are recognized by the Seven Shadows, to which she earn a "Named" Rank no. 22 and becoming Named Numbers when she would identify herself as Kai. Also, Kai established a strong and direct relationship with Epsilon, one of the original Seven Shadows, and worked together with Omega to become Epsilon's direct subordinates.

Sanctuary Infiltration
As the "Goddess's Trial" commenced in Lindwurm, Shadow Garden prepared for an infiltration mission, and Kai was present in the city. When Shadow suddenly made himself known to summon the memory of Aurora and concluding their battle with the result of Aurora's defeat along with the opening gate to Sanctuary at the same time, Kai was among the Shadow Garden contingent that followed Alpha, Delta, and Epsilon into the Sanctuary. Before entering the Sanctuary, Kai joined Omega by Epsilon's side as they taking Natsume Kafka a "hostage" and entering the Sanctuary, along with the Acting Archbishop Jack Nelson.

Inside, Kai and Omega followed Epsilon with a unit of Numbers to collect and gather all intelligence from the memory world they found within the Sanctuary, confirming some theories on the Cult's origins, learning new details, and understanding their motives much better. While the Slime Bodysuits were malfunctioning due to proximity to the core, Kai and Omega apparently imagined that Epsilon's (fake) breasts fell off and reattached, but when Epsilon was looking at them, they said nothing.

As their investigation mission are complete along with the information they collect from the Sanctuary, Alpha ordered all Numbers to leave which Kai complied and following her order to leave the Sanctuary, leaving Acting Archbishop Nelson to battle Shadow. Then, Shadow Garden's team was outside and Kai saw Shadow erased the Sanctuary using his "Atomic" spell. With the city flooded by the Sanctuary's destruction, Kai and Omega helped escorting Alpha and Epsilon out of Lindwurm with the intelligence they collected.

Powers & Abilities
Kai has been trained to use and control her magic, as well as fighting practices, based on lessons passed down from Shadow. Kai quickly rose through the ranks and making her one of the double-digit Numbers as a testament to her prowess and ability, which she are given a Greek name. She is eventually assigned to be the direct subordinate of Epsilon, one of the Seven Shadows.

Physical Abilities
Kai, like many before and after her joining, trained daily to improve upon her physical prowess. Such is necessary to be ready for a fight or to retreat to safety. This includes self-defense, martial arts, and strength training.

Swordsmanship
Kai is proficient with a blade, as are all of Shadow Garden, but Kai is likely a master to some degree having earned a Named Number rank, as well as serving as direct subordinate to Epsilon.

Magic
Kai is proficient in magic, having maintained her Slime Bodysuit during the magic distortion effects of the Holy Sanctuary Infiltration. Such is a requirement given Epsilon's renown within Shadow Garden for her refined magical control.

Quick Flash
A speed augmentation ability, derived from the early practice of speed magic Shadow taught the original Seven Shadows.

Standard Equipment

 * Slime Bodysuit: A standard issue in Shadow Garden, with Kai's having notable decoration to express higher rank and authority within the command structure compared to the rank-and-file.
 * The Rolapoid: An instant camera for missions of espionage, a reverse-engineered technology from Shadow Wisdom by Eta.

Cid Kagenō / Shadow
Kai is steadfastly loyal to Shadow, aware of his secret identity as Cid Kagenō. It was his methodology that developed a cure for Demon Possession and provided her a new purpose against the Cult for their conspiracy against her nearly taking her life.

Alpha
Kai as such, respects and obeys Alpha's orders as the one who directs everything by being the second in command, when her Lord Shadow is not present, in addition to having some security by having her as one of those who helped her, along with Epsilon.

Epsilon
Kai works as a direct subordinate of Epsilon, and is aware about her fake slime body, but pretends not to notice it as she cares about her.

Omega
As both are direct subordinates of Epsilon, both have developed an efficient process under their commander. Both have also shown a slight display of friendship when in their civilian dress.

Trivia

 * According to the director's tweet about Kai's illustration, the symbol to represent her name is χ, which is the 22nd letter of the Greek alphabet. In fact, the very first sentence from the Wikipedia page for the letter is already explains how to pronounced it.
 * Despite being women, Kai and Omega like to dress up as men occasionally. According to the two, this is so they can have other means of information gathering, unlike other Shadow Garden members. Although sometimes, they crossdress their clothes for fun.
 * Originally, according to some words from the author, when he was writing the characters of Kai and Omega, he had thought of making them the only men in Shadow Garden. But the idea was discarded, seeing the strong controversy that would arise with the story developing in the community. This is why the characters wear men's clothing, reflecting in some part of the author's discarded ideas.
 * Erroneously at the beginning, Kai and Omega were mistranslated as men in the Web Novel, before the anime premiered, which caused strong controversy in the Latin American and partly North American community when it was announced that all possible characters would be taken from the 3 versions of the story: the Manga, Web Novel, and Light Novel. But that would follow the Light Novel story route to which those translated were not fully corrected, until the full release of the anime and the game release.