Runaway Guide - Chapter 80

Lin Tianlong, 19 years old, a polytechnic school graduate. With mastery and control over electrical energy, he displays his unparalleled sagely medical skills, accepting the hearts of beauties on the side. Starting by helping his sister-in-law’s small clinic which was on the brink of closing down rise from the dead, he then proceeds to bring prosperity to a private hospital previously in a business slump. Socializing among the officials from the sectors of politics, commerce, law, literature, education, and health in Flame City, he’s drawn into the power struggle between the officials. Businesswomen, doctors, and nurses, attractive policewomen, teachers, pretty loli girls, charming married women, mature beauties – all of them fall to his clutches as he establishes his business empire and a harem of beautiful women.

- Description from Novelupdates

Cassian Ven Dyke, the bastard son of a powerful ducal family, grew up in the slums of Veldora under the care of his father figure, sword master Russel. When Russel passed away, Cassian was left with only a silver necklace as his inheritance. After putting it on, Cassian was attacked by three psychotic thugs who tortured him in an attempt to steal the necklace. Refusing to give in, Cassian was ultimately stabbed through the heart with the very same necklace. Instead of dying, he mysteriously vanished as the necklace lodged itself in his heart. Just before disappearing, he heard an eerie message echo in his mind:[True mana detected. Origin: Human...][Human detected. Compatibility with system: Confirmed.]

Mason was a mercenary, until the day he died on a mission after being betrayed by his unit.

I’ve reincarnated as the reverse harem game’s villainess, the one and only step-daughter of the Eckart duke family.