I Became The Villain The Hero Is Obsessed With - Chapter 299:

A little ruffian who fought recklessly without any morals and bottomline accidentally time-traveled to parallel space and became a Key Case Investigation Team agent. The huge change in identity had him creating chaos in the police station. However, a strange miracle system helped him repeatedly solve mysterious cases, turning him into an impudent ruffian detective!

After reviving unexpectedly, the concubine’s daughter was no longer a coward like before, but a hard nut.

Flamed her up and bullied her?

Come on!

She came from the 21st century! How could she willingly embrace such destiny?

“Since you ask for it, see how I will torture you!”

She punished the scums and struggled against bad minions!

See how the concubine’s daughter Dong Ling would stand up and master her own fate!

- Description from Novelupdates

«Until death do us part.»That was our vow.And she kept it... by driving her sword through my chest.I was a hero. A symbol. The one chosen by the gods to free humanity.I fought for her. For us.But in the end, it wasn’t the demons who killed me.It was the woman I loved.Helena betrayed me.I fell with my heart shattered and my blood burning between my fingers.But death wasn’t the end.I woke up in another body, in another world...No, not exactly.I woke up inside the very story she wrote.And now, I am Daven von Riesenhart:the bastard son of a marquess, a noble outcast with a name no one respects, and a life I never asked for.I no longer believe in ideals, in gods, or in happy endings.I won’t fight for others.I won’t die for anyone.This time, I’ll live only for myself.And if surviving means deceiving, betraying, or destroying...so be it.Even if it makes me the villain of this story.

An Individual from Earth finds themselves in the Shinobi World, equipped with a Scientific System. From that moment, he delved into scientific research far ahead of its time.