|Spoiler Alert: This article/section contains details about future plot lines described in the light novels, not covered in the anime. Do not proceed unless you want to be spoiled.|
|“||I don’t want to die…I want to live…I, I want to be with Yuzuru more.||”|
|“||Reply---Yuzuru….too. I don’t want to disappear. I want to live with Kaguya.||”|
Yamai was originally one Spirit, but for unknown reasons that may be related to her teleportation between dimensions sometime in the past, she was split into two bodies and minds. The original personality of Yamai is now gone, as well as what type of character she used to have is unknown to the split Yamais. The Yamai Sisters have been well known to the people who knew about the existence of Spirits because they often cause a major storm in an area, which occurs every time they come to Earth.
It was unstated when the Yamai Sisters started fighting, but they have been fighting with each other for quite some time for the sole purpose of deciding the winner as the real Yamai. Their matches range from non-violent to violent for almost 99 battles, with them arriving at 25 wins for each sister and 49 draws. They then decided that the 100th battle would be their final confrontation. Whether out of luck or by chance, the Yamai Sisters encounter Shido while he and his classmates were having a field trip to the southern island; the Yamai Sisters decided that their 100th battle should be whoever can seduce Shido first will be the winner and will be considered as the real Yamai. It was around this time, thanks to Reine, which the Yamai Sisters transfer into Shido’s high school and the beginning of both Yamai sisters and Shido's battle to seduce each other.
In reality, both of the Yamai Sisters secretly wanted the other to live, but when they discovered that both of them have the same idea, they stubbornly refuse themselves to live and for the other to die; so in the end, they fought. Thankfully, Shido forcefully interrupted their fight with Tohka’s sword, Sandalphon, and gave them a new option for both of them to live and that is for him to seal their power. They pondered on that idea until they finally accepted their wish to live along with each other. Both of them got their power sealed at the same time when they gave Shido a thank you kiss.
Due to their stable mental state after being sealed, they didn't need to transfer into Shido's classroom, but the one next door to his.
Being identical twins, Kaguya and Yuzuru look almost the same. They both have orange hair, with a long strand on each side of their head ending in a tornado-like twirl. They also have mercury blue eyes and are close to the same height. However, watching carefully, both still have their individual characteristics.
She has "a characteristically delicate body that looked like it would break if hugged too tightly" as described by Shido. Her hair is braided up, and she has a lean figure. She has a determined expression for most of the time. Kaguya's height is stated to be 157 cm, and her three sizes are B79/W56/H81.
Kaguya's Astral Dress is mainly the color purple and has chains on her right hand and foot. The lower half of her body has a half skirt around her waist which drops to the knees and opens around her thighs. As for casual attire, she began wearing the Raizen High School uniform during her first date with Shido and later adopted the full outfit upon enrolling, including the vest. Aside from this, Kaguya is a fan of gothic lolita outfits. While her fashion sense has been noted to have become more mature by the time she entered university, she still prefers black clothes.
She has "the body of a model" as described by Shido. Her hair is braided in three portions, and she has a curvy figure. She has a vague expression and keeps her eyes half closed for most of the time; simply put, Yuzuru has a poker face. Her height is stated to be 158 cm, and her three sizes are B90/W61/H86.
While her sister's Astral Dress is mainly purple in color, Yuzuru's dress is bluish-purple with a small cape and has chains on her left hand and foot. As for casual attire, she began wearing the Raizen High School uniform during her first date with Shido and later adopted the full outfit upon enrolling, including the vest. Aside from this, in contrast to Kaguya, Yuzuru seems to prefer more mature clothes.
As their original, the human Yamai looked identical to Kaguya and Yuzuru, to the point that the twins initially mistook her for each other upon seeing a picture of her. She was also noted to have been beautiful enough for a modeling agency to attempt to scout her.
The appearance of the fused form of the Yamai sisters differs from the human Yamai in several ways. Particularly, she herself noted that she is both taller and bustier compared to her human self. Shido describes her facial features as being an "in-between" of Kaguya and Yuzuru's looks. Also, unlike the twins, Yamai does not braid her hair in any way. Her height is 180 cm, and her three sizes are B102/W66/H98.
Yamai's Astral Dress combines the colors of both sisters, and has a complete pair of wings. Her outfit also includes several extra pieces of armor as well as a long muffler around her neck. As for casual attire, in Yamai Triad, she wore the Raizen High School uniform. However, unlike the sisters, she opted to omit the vest. Also, the uniform was comically under-sized on her, leaving her bust and upper-tights partially exposed.
Despite being twins, their personalities are almost complete opposites to each other. However, they still have some things in common, with both having displayed a playful attitude as well as a mutual love for competition and each other.
Outgoing and outspoken, one can say that she is childish or immature. Kaguya appears to suffer from Chūnibyō, often using with exaggerated gestures and German words in an attempt to sound cool. However, she is perfectly capable to speaking normally and her act quickly falls apart if even slightly pressed upon, causing her to often be teased by others. She is also weak about sensual matters and is easily embarrassed when they are mentioned.
She speaks in a robot-like speech pattern, telling the point of her comment before speaking the rest. For example, when asking Shido to explain something, she would say "Confirm; Shido". Also, unlike with Kaguya, her speaking patterns are a genuine verbal tic and not just an act. When arguing with Kaguya, she tends to sneer at her and points out the flaws in her arguments. Overall, Yuzuru is the calmer, quieter, and arguably the more mature one of the twins, though she still has her own moments of childishness.
The human Yamai appeared to have been a sociable and popular, yet ordinary, teenage girl. She was shown to be incredibly selfless, saving child from getting run over at the cost getting fatally injured herself. However, she was also somewhat childish, thinking she would be viewed as a hero, though this was partially to mask her fear upon realizing that she was dying. Even in her final moments, Yamai continued to place other above herself by worrying what would happen to them following her death.
As a Spirit, Yamai's personality is a combination of the Yamai sisters, starting her sentences with a summarizing word like Yuzuru and continuing with eloquent speech like Kaguya. However, again like Kaguya, she can also continue with normal words. She inherited the twins' playful demeanors and competitive natures. In fact, in Yamai Triad, she was shown to arguably be too excitable, causing her to be ignorant to others' feelings and health. However, she is far from selfish, being ashamed of her bad habit when she notices it.
Yamai Kazamachi was born a vanishing twin, with her absorbing her stillborn twin while still in utero. She grew up to become an ordinary high school student heavily involved in anything she could participate in like music and athletic activities. One day, around at the age of 17, she saw a child that was about to be hit by a vehicle. Wanting to be like a hero she always admired as a kid, she moved to save the kid at the expense of being struck in that child's place. As her consciousness started to fade, Mio appeared and gave her a Sephira Crystal to save her life. However, rather uniquely the Sephira reacted bizarrely with the DNA of her stillborn twin sister as well, causing the original Yamai Kazamachi to split apart into two. The subsequent twins Kaguya and Yuzuru then both inherited different aspects of the original's personality and preferences. Over time both twins forget about their human life, only remembering that they both originally came from one Spirit called Yamai.
The Yamai Sisters subsequently became well known to the people who knew about the existence of Spirits because they often cause a major storm in an area, which occurs every time they come to Earth. It was unstated when the Yamai Sisters started fighting, but they have been fighting with each other for quite some time for the sole purpose of deciding that the winner will become the real Yamai.
- Light Novel
- Volumes 5-22
- Date A Live Encore 1-11
- Date A Live Material 1-2
- Date A Live Another Route
Powers and Abilities
Due to having their Sephira Crystal split in half between each other, both twins share the same powers commanding wind. In terms of speed, they are regarded as the fastest Spirits. After hearing that they were originally one being, Reine theorizes that Kaguya and Yuzuru have their own unique Path that circulates Reiryoku between the two of them. She compares it to the Path which Shido establishes after sealing a Spirit.
Both of the Yamai Sisters, despite using different weapons; have the power to manipulate wind. They can gracefully control the air currents in order to glide through the sky. At their full power, both of them can easily create a typhoon that can blow away a small island. They also have shown to be able to combine their powers to form a bow and an arrow that is able to pierce through the <Arbatel>'s Territory.
- Kaguya: El Re'em (
穿つ者, Eru Re'emu?. lit. "Piercer")
- Yuzuru: El Na'ash (
縛める者, Eru Nahashu?. lit. "Constrictor")
- Combination Attack: El Kanaph (
天を駆ける者, Eru Kanafu?. lit. "Sky Rider"): A single decisive blow fired from a combination of the Yamai sisters' individual Angels. Both of their wings combine to form the body of the bow, Yuzuru's pendulum becomes the bowstring, and Kaguya's lance becomes the arrow.
After being forced to see Ellen kill Shido on the school rooftop, both of the twins, along with Tohka and Origami, assumed their inverse forms due to the overwhelming despair in their hearts. In this form, the Yamai sisters were both surrounded by a tornado that indiscriminately rampaged around the buildings beside the school. However, the status quo was restored after Kurumi used the sixth bullet to travel back in time.
Upon taking in Beast's Eighth Sword, both Kaguya and Yuzuru grabbed the spiral blade at the same time and kiss, causing their bodies to temporarily merge and fuse as one. In turn, this causes a recreation of the original Yamai Kazamachi to be reborn. However, Yamai considers herself different than the human Yamai Kazamachi due to the personal growth that both Kaguya and Yuzuru have developed after splitting apart. The fusion grants enough strength and speed (the latter reaching supersonic levels) to overpower Beast after she had already been weakened by Origami and Kotori's attacks. However, as a forced fusion, there is a time limit set before both Kaguya and Yuzuru are forcibly split apart again, which does occur shortly after their fight with Beast concludes. Nevertheless, their fusion allows Yamai access to <Raphael>'s full power, combining Kaguya and Yuzuru's individual weapons together for various defensive and offensive purposes.
- El Tsuofuel (
貫く者, Eru Tsuofueru?. lit. "Piercer"): Fusing her chain to the handle of her lance, her weapon becomes a guided projectile that can be steered through manipulating the chain portion. Even if the lance is dodged, the sheer wind pressure coating the weapon is enough to push back the target.
- El Peguz (
護る者, Eru Pegutsu?. lit. "Protector"): By wrapping her chains around her folded wings, Yamai creates a sturdy knight's shield that can be used to defend against incoming blows. The shield itself was durable enough to endure a direct guided slash from <Beast>'s Sandalphon.
- El Yevurn (
蒼穹を喰らう者, Eru Ievurun?. lit. "Consumer of the Blue Sky"): By fusing all of the components of her Angel together with portions of her Astral Dress, Yamai summons a huge ballista that can fire a pure concentrated arrow of wind pressure.
As Spirits, Kaguya and Yuzuru boast physical abilities far above those of an average human even whilst sealed. Like Tohka, they also seem to be able to instinctively sense an opponent's strength.
As a result of their many matches, the Kaguya and Yuzuru have developed a huge amount of miscellaneous skills, being experts in anything from makeovers, to drawing, to video games, to bowling. However, there are also some skills that only one of them has, with Kaguya being better at playing drum sets whilst Yuzuru is more skilled with bass guitars and word games.
In Yamai Triad, Yamai Kazamachi was shown to have the same miscellaneous skills as Kaguya and Yuzuru. However, she possesses an even higher level of mastery, easily besting her separate selves in everything from arcade games, to cosplay, to rhythm games, to even a bowling game where the twins were allowed to add their scores together. In the end, Yamai had to handicap herself by partnering with Shido just to give two of them a fair chance.
- (To Shido Itsuka) "……………It's better if I don't know right………then, I'll believe you. That's because, Shido was the one who gave me and Yuzuru the 3rd choice at that time……………." 
- (To Shido Itsuka) "Convinced. Kaguya is often like that but, she really loves Shido. There is no mistake since Yuzuru says this. Yuzuru and Kaguya were originally from one body and one soul. What Yuzuru hates, Kaguya also hates. Similarly---------what Yuzuru loves, Kaguya also loves." 
- (To Shido and the Spirits): "Intrusion. For those afar, heed my cry. Gaze closely if you will. One horseman equal to God. To solve this dilemma swiftly and skillfully. ——I am Yamai Kazamachi, the typhoon king who reaps all of creation.
- Yamai was the original Yamai Kazamachi's given name. However, after splitting apart, both Kaguya and Yuzuru adopt Yamai as their shared surname.
- Yamai has the "Eight" character in her name (「八」舞). It refers to eighth Sephira on the Kabbalah's Tree of Life: "Majesty or Splendor."
- Kaguya's name contains "arrow" (矢, ya) and Yuzuru's name contains "bowstring" (弦, tsuru).
- Kazamachi contains the kanji for "wind" (風, kaza) and "wait" (待, machi).
- Oddly Kaguya and Yuzuru's angel is supposed to be Michael because Raphael governs the sixth Sephira on Kabbalah's Tree of Life, "Beauty," while Michael governs the eighth Sephira on Kabbalah's Tree of Life, "Hod", which means "Majesty" or "Splendor".
- However, Raphael and Michael are said to co-operate on the governing of the 6th and 8th sephirot, therefore both can be said to be affiliated with those sephirot. The fact there are two Yamai spirits illustrates the point that it has two governing entities.
- The Yamai sisters' Astral Dress's name is 'Elohim Tzabaoth' which means "God of Hosts or Armies." (Derived from the two Hebrew word: "Elohim" Which means God in Hebrew and "Tzabaoth" a Hebrew word which means "Host" or "Armies").
- Their angel, Raphael's name means in Hebrew was "God has healed" or "God's healer," Which "Raphael" was one of the Seven Archangel that appeared in the Book of Tobit.
- The actual meanings of El Re'em (ראם), El Na'ash (נחש), and El Kanaph (כנף) are "bull", "serpent", and "wing" in Hebrew.
- The Yamai sisters appear in the Date a Live OVA as a cameo at the arcade which Tohka and Shido are at.
- Any word Yuzuru starts her speeches with will always have exactly two kanji in Japanese.
- Kaguya loves cool things and hates studying. Yuzuru loves junk food and hates noise pollution. 
- Raphael was decided on having a wind attribute early on, but the Angel's form was not always a bow, with some ideas including a centaur or a chariot. The Yamai sisters' Astral Dresses also had concepts like "bandit" or "sylph" before "bondage" was settled on.
- Yamai Kazamachi's unborn little sister would have been named Yayoi (八宵). 
- In the early drafts, the twins’ names were Tenma and Chikage Yatagarasu (
八咫硝子 天真と地景?). 
- Yamai Kazamachi likes heavy metal and dislikes crown daisies.
- As an anthropomorphic disaster, the Yamai sisters represent typhoons.