Hell Teacher Nube OVA (1998)

When a mysterious villain threatens to open the gates of Hell, a devilishly handsome demon hunter could be the world's best hope for salvation.

Accused of murder and thrown into the Pit, a young orphan joins a group of monster fighters with special powers to uncover the truth and seek vengeance.

Witches were once respected for the wisdom and magic they gifted to humans. But with the rise of the Gear Expansion era, the new science community deemed them as enemies who hindered the progress of society. Thus began the slaughter of all witches, including one who had mentored a human boy named Adonis. After witnessing her death, Adonis vows to bring bloodshed and terror to the human race.

To gain the skills he needs to surpass his powerful father, Baki enters Arizona State Prison to take on the notorious inmate known as Mr. Unchained.

With a demonic, soul-consuming weapon in hand, can a legendary swordsman and a samurai brotherhood defeat a bloodthirsty zombie uprising?

It has been 800 years since the incredibly fast and powerful gods of battle known as the Idaten had sealed away the demons after an intense battle. Now, that battle is just considered a myth or a fairytale. While the current generation of Idaten who have never even had to fight are enjoying their peaceful lives, someone awakened the demons once again! Armed forces, ingenuity, politics, and intrigue. If you've got it, use everything you can! This three-way battle royale with no rules and no limits is about to begin!!

The Great Jahy, the Dark Realm's second-in-command, cuts a frightening figure, feared and revered by all. But when a run-in with a magical girl results in the destruction of the precious mana crystal, the Dark Realm falls, transporting the newly tiny and powerless Jahy to the human world! Unfortunately, plotting the revival of the Dark Realm from a cramped, crumbling one-room apartment is no easy feat when you have rent to pay and a job to keep!

As a legendary hero nears victory against a necromancer known as The Corpse God, things take an unexpected turn with the dark sorcerer’s final gambit—reincarnation magic. This last-ditch effort catches the brave fighter off guard, and now he’s a boy named Polka Shinoyama in a whole new world! The showdown between good and evil just got epic.

During the Warring States era, the feuding generals were suddenly struck down one after another by the demonic Kishin. In the 150 years since, groups of individuals have continued to resist Kishin control. They are called Bushi bands. When they were young, Musashi and Kojiro would hear tales about the Bushi from Kojiro's father, and the two of them dream to form the strongest Bushi band. One day, as Musashi struggles with his choices, he witnesses humans being torn apart by oni. Forced to face the truth, Musashi rises up against the powerful oni to make his dream with Kojiro come true!

In the year 2024, the world has collapsed. Grotesque monsters lurk amongst the ruins of Japan, while remaining people scrape together what they can to survive. Kiruko, an odd-job girl in Nakano, accepts a mysterious woman's dying wish to take a boy named Maru to a place called Heaven. Maru is convinced that there will be a boy there who looks exactly like him.