I Shaved. Then I Brought a High School Girl Home. - Volume 1, Chapter 8: Mishima Yuzuha

When a traverser mistakenly thought that he had crossed the back of Britain in the 1980s, and when he was suffering from childhood, he would eventually sink into the darkness in repentance, and a strange and familiar admission notice would light up his life.

But when he came into contact with the deeper darkness, did he choose to stay away from the abyss or jump into it without hesitation?

”You wait, I will be back soon.”

On the fifth floor of the St. Mungo Hospital, he finally firmly held her pale hand.

This is a story of biting teeth, even a liar that you can lie, and struggles repeatedly in pain and tenderness.

- Description from Novelupdates

Talent.As a demon born into a prestigious family like the Tenebris, Cale lacked nothing, except talent.Talent, to surpass his twin sister, who was better than him in every way.Talent to earn the approval of their mother, the cold and ruthless Matriarch.It wasn’t mere rivalry; his very life depended on it.But, no matter how hard he trained or how low he stooped, using forbidden methods to grow stronger, he never succeeded. He couldn’t awaken his bloodline, nor defeat his sister in a single duel.“Just give up already. You’re only making it more painful for yourself,” she would say every time.He was pathetic, and he knew it.But giving up on life was never an option.“One more time... I’ll try it one more time.” That was how he always responded to her scorn.Was it ego? Or a desperate desire to prove everyone who waited eagerly for his downfall wrong?Cale didn’t know. But he always stood up again.No matter what they said, he refused to surrender.Not to his mother.Not to the world.Not even to his sister.If the world stood against him, then he would crush the world.-------------------------“Wow. That’s an incredible backstory for a villain.”I flipped through the worn pages of an old book, my only functional eye open wide.“But where did this come from? It wasn’t here before.”I’d read this romance fantasy novel back in my childhood, and as far as I remembered, Cale Tenebris never had a backstory.“Did I grab the wrong book?” I tilted the cover to check the title.[Curse of the Crown]It was the same one.“Did I skip this chapter before?... Whatever.” I shrugged, turning the page again as I slowly lost consciousness.And then I died.

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.