Yokai (妖怪 Yōkai) are creatures that live in Elentear.
- Lifeforms (生命体 Seimeitai): The Lifeforms appears as generic humanoid shadow-like entities.
- Snow-Woman (雪女 Yuki-Onna): The Yuki-Onna's real appearance is unknown since it takes the forms of the women sleeping in the depth of their target's hearts through the use of snow.
- Ittan-Momen (一反木綿 Ittan Momen): The Ittan-Momen appears as a monster made up of bandages that they can use as constraints.
- Fire Cart (火車 Kasha): The Fire Cart appears as a flaming carriage-like Yokai with cat-features that leaves a trail of flames in its path.
- Smoke Warrior (煙煙羅 Enenra): The Smoke Warrior appears as a cloud-like Yokai that uses smoke in its attacks.
- Nure-Onna (濡れ女 Nure-Onna): The Nure-Onna appears as a humanoid Yokai with an upper-body of a female human with scales on its shoulders and arms as well as a lower body of a snake. It can also turn its upper body into water and uses it against its enemy.
- Bakeneko (化け猫 Bakeneko): The Bakeneko appears as a humanoid Yokai with the features of a human, but the ears, whiskers, tail, and paws of a cat.
- Suiko (水虎 Suiko): The Suiko appears as a large, tiger-like Yokai.
- Spider Woman (女郎蜘蛛 Jorōgumo): The Jorogumo appears as a humanoid Yokai with an upper-body of a female human and a lower body of a giant spider.
- Ōmagatoki (逢魔時 Ōmagatoki): The Ōmagatoki appears as a humanoid Yokai with a pair of large horns on its head, a pair of pointed ears, two pair of arms wielding swords on each hand and black line designs all over its body.
- The literal English translation for "Yokai" is "monsters".
- A large number of unnamed Yokai appear in Oni-Ga-Tsuki; most of them reflecting the Japanese monsters, such as a number of Tsukumogami and a Noppera-bō.
- More unnamed Yokai that are summoned by Yoko reflect several more Japanese monsters, such as a Gashadokuro, a Rokurokubi, a Tengu, an Oni, a tall woman with long arms and legs may reference the Hachishaku-sama, a Namahage, a catfish monk resembling the Iwana-bozu, and Tsurube-otoshi. Several more appear including a Hyakume, a Kappa, a Nuppeppō, a Ningyo, and a Tanuki.
|Earth Land||Artificial Lizardman • Bakshi • Celestial Spirit • Clipper • Curily • Demon • Doscadon • Dragon • Etherious • Exceed • Fish • Giant • Goblin • God • God Seed • Grand Magic Games Monsters • Hane-Sakana • Hodras • Cubina Gamal • Lizardman • Machias • Mole • Rollidillo • Spirit-Luminescent Bug • Tenrou Squirrel • Vulcan • Weretiger • Wyvern|
|Elentear||Exceed • Tsumeaka • Yokai|