Harry Potter: Dimensional Wizard - Chapter 646: Avengers' Training: Iron Man

Vergil, a 21-year-old young man, leads an apparently simple life in a somewhat troubled world. His family is also simple—although his father is no longer alive, his mother has always been by his side, despite being a bit... aggressive. But that's not so unusual nowadays, right?Everything changes drastically when Vergil, after an unexpected death, awakens as a demon. To his surprise, he discovers that he has accidentally married beautiful Pure-Blood demonesses.Now, he will discover how the world really works from a Demon's perspective.

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.

Bai Xiaocheng was hit by 200 million, really 200 million, one? Pan Kochang?

- Description from novelbuddy

Seeing the cause of justice, the student Ning Tianlin, who was strangled, accidentally gained a combat system in the local government and returned to Yang.

What the hell, your fighting power is only fifty, then you still pretend to be me! I’m sorry to tell you 10,000 points of combat power!

What are you doing, have you been boiled down, trained in martial arts, and practiced iron gear? The fighting power is five hundred? That has something to do with me, I won’t tell you, the clothes I wear, but combat equipment! Just a single underwear, can add a thousand fighting power to me!

Hey, why do you say my combat power has increased so fast? Can I tell you that if I step on an ant and destroy a cockroach, can I increase my combat effectiveness?

- Description from uukanshu