I Never Run Out of Mana - Chapter 165: Towards the Demon King (United by Steak)

Song Yan, a senior high school student, lost his parents when he was a child. Before obtaining a mysterious and amazing ring, he has been often plunged into a vulnerable position and easily marginalized. However, his life is changed because of the cryptic ring.

- Description from Novelupdates

After his death, Bern awakens 10 years into the past as the third prince of Kailis, the enemy country.

Damien reveals an ugly truth.His sister and only family, Ahara, leaves the house every midnight whilst he's asleep—a time that he soon discovers is when man-eating beasts named Rouges start hunting for prey.Unable to question her directly, he decides to investigate her and quickly figures that Ahara isn't human but rather, a vampire hero who saves them from beings like herself coming from a world she calls Gibbous—a place where entities like vampires, wizards, and beast shifters alike reside. What’s more, he also learns that the real reason behind his parents' death was the leader of the Rogues, who's rumored to have escaped after Damien’s father almost killed him.A series of fateful events lead to Damien’s long-lost power reawakening in him, and he finds himself with no choice but to return to Gibbous, a strange world where power means survival, and weakness leads to death. As such, Damien enrolls in an academy to train his newfound abilities with one thing in mind...Becoming more powerful.However, he soon discovers that the path to power is one filled with troubles and pain, and he isn’t alone in this lust for more at the academy. It’s a bloody competition against time and formidable opponents, and only those willing to sacrifice their comfort are the ones who can attain it.With a deadly foe lurking in the shadows somewhere and a strong desire to protect his sister, Damein has no choice but to fight.The only way is up, and he is going to be standing at the top of them all, ready to counter any enemy.

Yang Feng somehow transmigrated into a different world and received a legacy of an ‘ancient high tech’ family, which does not directly raise his power, but gives him the technology to build things which are way more advanced than the seemingly medieval world.