Legules (レギュレイス Regyureisu?) is a Horror that has existed for over 1,000 years. The Makai community has no recorded history and his movements have no records. One thousand years ago during a solar eclipse, Legules successfully crossed through the barrier between worlds and revived his followers known as the Legules Family. Many Makai Knights and Makai Priests died that day in order to suppress the Horrors that Legules unleashed on humanity. To make sure that the catastrophe would never happen again, the Makai Priests created the Phosphorus Arrow to destroy the barrier and seal away Legules. One thousand years later, Legules manages to find another gateway to return to the human realm by assimilating a dead body to make it his own. Legules is not the usual variety of Horror, as he is seemingly demi-human and possessing elementals similar to Oni or Yokai.
He quickly begins building forces of his own by converting Horrors and a human into "his family". He then attacks Kantai in the middle of night to find the Phosphorus Arrow so that he can complete his task of reviving his family. He tries to convert everyone, including the Madōgu of each Makai Knight, to join his forces. Tsubasa's Madōgu Goruba somehow gets possessed and controlled his bracelet body. When the night raid fails, he transferred himself into Goruba during the day and comes when people least suspected anything wrong. Legules takes the arrow and Rin Yamagatana with him, as he needs her blood to activate the arrow.
Legules's capabilities include, and are not limited to, bodily assimilation, dark magic, immunity to regular physical attacks, human energy absorption, body transference, martial arts, ultra human strength, ultra healing, body parts that can move without attachment, and biological transfiguration. Once the eclipse begins, Legules transformed himself into his true form, a giant metallic skeleton-like Horror. In this form, he is able to transform into a bladed metal wasp. Legules is defeated when Garo throws the Phosphorus Arrow into him and destroys the barrier at the same time. With Legules destroyed, the demon family vanishes.
Legules is portrayed by Mizuho Yoshida (吉田 瑞穂 Yoshida Mizuho?) and is voiced by Hirose Masashi (広瀬 正志 Hirose Masashi?).