TV-Series
Description
Janua Ein is one of twelve powerful demons named after the months, representing January. He has bobcut black hair covering his right eye, a golden earring on his right ear, and heterochromatic eyes—red left and blue right. A drawn-on crescent scar sits beneath his left eye. His attire varies, from a prison uniform to a black work suit with a pale blue undershirt, or situation-specific clothing like a soccer uniform.

Janua is intensely enthusiastic about ninjas, labeling all his magical abilities as "ninjutsu" and frequently using the verbal tic "degozaru." Despite immense power, he is inherently good-natured, avoids lethal force due to a reluctance to kill, and often holds back in combat. Generally cheerful and helpful, he becomes easily distressed, such as when forcibly proposed to by Hasegawara, and later expresses frustration at being used solely for teleportation.

His background includes imprisonment for accidentally demolishing a building while reaching for ketchup, a result of his strength and clumsiness. He shares a past with the demon Samejima from their school days. He first meets protagonists Alba, Ros, and Ruki in prison, breaching their cell wall to introduce himself. He later allies with them, bonding with a cat named Mii-chan, who mutates in size due to prolonged exposure to Janua in the human world.

Key involvements include being brainwashed by the demon Zwei, leading him to take Ruki and Mii-chan hostage; Samejima breaks the brainwashing by punching him. During a soccer match, Janua volunteers as a distraction against adversaries like September, using techniques like the "Thousand Arm Buddha" before being forcibly returned to the demon world via a portal. In the demon world, he cultivates tomatoes. He later aids Ruki in locating the missing Alba by teleporting the group to him.

Later, Janua is captured by Hasegawara demanding marriage. Forced into the "Demon World's Decisive Number 1 Strongest Tournament," he initially seeks Samejima's help but ultimately confronts and defeats Hasegawara independently in the third round, reuniting with Alba and Ros afterward. When encountering Samejima battling Rchimedes, Janua attacks Rchimedes to protect his allies, declaring defiance despite not knowing the foe, and is subsequently incapacitated by Dezember.

Janua's abilities center on potent magic. Teleportation is his signature skill, allowing travel vast distances within a single world or entry into dimensional rifts, but he cannot cross between worlds; he can locate individuals and transport to them. He wields formidable offensive magic capable of breaching solid structures, though rarely employed lethally. Additional techniques mimic ninja tropes, like the "Arm Clone Jutsu" where he spins his arms to create illusions. His considerable physical strength causes accidental destruction. A side effect of his magic causes mutations in beings exposed to him for extended periods.