Eyrith (or Eiris) is the featured Horror in The Makai Flower. She is a legendary Horror that earned the moniker of Messiah's Tear (メシアの涙, Meshia no Namida) and Black Death Demon Flower. Unlike other Horrors, she's a plant-based demonic entity and has powers and abilities unique to only herself.
Eyrith is one of the most powerful, intelligent, and resourceful of Horrors. She is highly confident, egotistical, and ambitious. Eyrith has the power to manipulate space and time, including recreating life through genetic absorbtion. Eyrith couldn't be defeated by conventional means, the Makai Priests had converted nine Horrors into Ady Slates just to seal her. She was merely weakened and contained but never killed. When released, Eyrith was in her sapling form, able to transfer and hide into any one of the Ady Slate Horrors. The only way to truly corner her was to capture all the Ady Slate Horrors to force her to reveal herself. Even as a sapling, Eyrith can speak, fight, posses a person, and clone a dead person. In her fully sprouted form, she was nearly unstoppable as three knights and a priest wasn't enough to stop her.
Eyrith was sealed long ago by the Makai Priests within the Ady Slate created from using nine Horrors as foundation stones. However, the Ady Slate was lost to myth until was found in the present day by archaeologists. The slate ended up in a museum as an archaeological relic until Eiji Busujima, who believed the legend that Eyrith's bloomed state, the Makai Flower, can bring back his lover Akari, broke the seal and unleashed the Horrors that formed the Ady Slab as they each took the first human host they come across.
Trapped in the form of a seed until she is able to bloom within a hundred days, Eyrith resided deep in the body of Idora as she and other Ady Slab Horrors were being hunted by Raiga Saejima and Mayuri, the latter able to seal Eyrith. But as Raiga learned from his confrontation with Idora, Eyrith can transfer herself into another Ady Slab Horror as she did with Gogeet as Raiga sees slaying all the Ady Slate Horrors would be needed to corner Eyrith. However, when Eyrith transfers into the last Ady Slate Horror Jienda as the day of her blooming is near, Eyrith's seed is extracted by Busujima as he forms a pact to protect the Horror in return for a cloned body of Akari that will come to life once Eyrith blooms. But as Busujima fights off Raiga, Eyrith acts on her whim and possesses Crow to reach the location where she must be to bloom while wounding Busujima when he decides his deal with the Horror is not worth Crow's possession.
Raiga pursues Crow, disarming him so he can save him before Eyrith leaves his body and assumes a human-like form before growing into a giant tree and using her power to absorb all Horrors from time and space. With Mayuri unable to seal Eyrith until her unbloomed bulb is destroyed, Raiga attempts to perform the deed before facing a construct of Eyrith. During the losing fight, Raiga learns that Eyrith is the one responsible for the disappearance of his parents Kouga Saejima and Kaoru Mitsuki before she sucks his remaining time in the Garo armor to force him to undergo Lost Soul Beast Transformation and redirect his focus of rage onto Crow and Mayuri.
This endeavor ultimately backfires, as when the Horror corners Mayuri, Mayuri dropped Akari's bell which then lands onto Raiga, which light aided him overcoming his inner darkness and granted him access to Light Beast Awakening Garo form. With his newfound power boost, Raiga battles Eyrith once more and overpowered her. As he did, Raiga pointed out that her plan in sending an army of her brethren across multiple timelines is flawed because the Horrors she has summoned have already been killed by his predecessors and other Makai Knights across the said timelines before finally destroyed her. With Eyrith's physical form destroyed, Mayuri quickly reforms Ady Slate to seal Eyrith once again and ending her threat.
- Time & Space Manipulation: Eyrith has the power to open portals throughout time and space. She can create time portals to communicate with past entities or send someone into a different dimension. She used one of those portals to take away Raiga's parents, Kaoru is lost in between worlds and Kouga is searching for her. She even brought back Zaji. Her abilities seem to be limited to only past and present time manipulation though, as she never once seen opening a portal into the future, only to various times of the past.
- Cloning: Eyrith can bring back the dead if she is giving sufficient genetic material. She can use a dead person's hair and take the genetic material to fully replicate a body. However, without the soul, the body is a revenant. In theory though, if you can reintroduce the body with a soul, you could fully restore a dead person back to life. It was a theory Wicked Bones Knight Eiji Busujima used in an attempt to bring back his beloved Akari.
- Body Possession: She can take over another person's body, fully taking over their body and mind. She took over Crow's body and can even summon his armor and fly off.
- Body Transference: This ability seems to be limited to only the Ady Slate Horrors. The very same Horrors that were used to seal her gave her the unique ability to transfer and hide inside of them. Should an Ady Slate Horror be defeated, Eyrith can instantly transfer herself into another Ady Slate Horror. Only when all the Ady Slate Horrors are captured that she can fully reveal herself.
- Weapon Creation: Using her own body, she can make a vast array of sharp objects to stab and cut against an enemy. She can create a series of sharp blades that can fly off like shurikens and can use her plant appendages to grapple and whip against the opponent.
- Energy Absorption: In her fully developed form, her body can absorb various energies, including the energies of the Earth to power her. She can also use her plant appendages and absorb the energy out of makai armor. She actually burned out the time limit of the Garo armor, forcing Raiga to become a Lost Soul Beast.
- Telepathy: Eyrith communicates with others, Horrors or sentient beings like humans via. telepathy, as during her confrontation with Garo, her mouth not visibly moving when taunting the Golden Knight.
- Eyrith is portrayed by Momoko Kuroki (黒木 桃子 Kuroki Momoko) who also played Yukihime.