Battlefield, Sunrise.

A woman with black eyes with red irises and white hair wearing a red cape, pair of white pants stained red with blood, black shoes that were also stained red with blood, and a red cloth across her chest for modesty stared at her surroundings in horror while wielding a sword in each of her hands. 'What... What the hell am I becoming!? I slew over a thousand Demon Lords and 99 Overlords without even breaking a sweat!? No normal Demon would be able to do this!' the woman thought to herself before continuing, "Could I be on the verge of becoming something even worse than a Demon!? If so, then there is only one way that I could possibly do to prevent that."

The woman then proceeded to create a large magic circle around herself and poured power into it. The magic circle proceeded to glow an immense white light for five minutes and when it died down, the woman was no longer there, but in her place was a tear in the dimensions. On the other side of that tear was a school known as Kuoh Academy, an all-girls school that had recently gone co-ed. Looking into the tear was a male Demon with solid red eyes wearing a long flowing black cloak over most of his body, yet the hood was drawn back to reveal his head.

"I sense that some of Overlord Zenon's power went through that tear in the dimensions, but she would not have gone through. I need to find her to get my revenge. Maybe she went to that backwater human world known as Veldime." the Demon spoke before leaving.

At Kuoh Academy, a figure similar to the woman had arrived at the training hall and spotted two teenage boys trying to look through a peephole while a third one noticed her and gulped in fear. The woman looked at the brown-haired young man in front of her and judging him to be not worth killing, she said, "You're so pathetically weak right now that you're not worth killing. Get out of here before I change my mind."

Issei heard the menacing tone of her voice and then ran away. The woman then got behind Matsuda and yanked him back before she tore his head off his body. She then dropped his corpse and summoned a sword that she used to stab Motohama through the back of his head before pulling it out and decapitating him. The woman then proceeded to eat the two corpses in just six minutes, at which point she found herself surrounded by the horrified members of the Girls Kendo Club.

"You... you just killed and ate two members of the Perverted Trio!" one of the girls exclaimed.

Upon seeing their shinai, the woman asked the girls around her, "Are you my enemies?"

Katase and Murayama immediately dropped their shinai and fled while a second girl asked, "What!?"

"Are you my enemies? I won't say it a third time." the woman spoke.

Upon hearing that, one of the girls attempted to attack the woman only for the Overlord to cut her in half with her sword. She then spoke, "I take that as you are my enemies. Very well, I shall show no mercy to any of you! Know that you have drawn the wrath of Overlord Zenon!"

The result was a one-sided slaughter. Zenon cut down the Girls Kendo Club without any of them managing to land a single hit on her and her sword broke their shinai with a single blow. After only a minute of battle, Zenon stood in the center of a ring of dead girls. She said nothing as she left the area, which unknown to her had been observed by a red-headed girl and a black-haired girl who wore glasses.

"There's no mistake about it, Sona. This 'Overlord Zenon' is extremely dangerous, given how swiftly she murdered most of the Girls Kendo Club. The only ones not killed were Katase and Murayama, and they wisely fled rather than fight." the red-headed girl spoke.

"That is true, Rias. Even though we should do something about Zenon, she is way too powerful for us to fight, and I fear that not even our older siblings are strong enough to defeat her. We need more time to think on this. The police will simply get slaughtered." the black-haired girl, Sona, replied.

A Dimensional Gate appeared on the roof and a green-cloaked Spirit emerged from it before it remarked in a masculine voice, "Indeed, but what has appeared was not the real Overlord Zenon. Merely a shadow, born from her wrath."