Eternal Thief - Chapter 15 - Sneak Inside Inner-Region!

Holo’s life was once a series of relentless hardships—bullies at school, abusive parents, and heartbreak at the hands of those he trusted. After a failed suicide attempt, a mysterious man offers him a deal: help rehabilitate four psychopathic girls, and in return, earn ten million dollars. Desperate and naive, Holo accepts, not realizing the chaos and danger awaiting him.Each girl comes with her own dark tendencies—Trixie, a violent and feral girl who acts on impulse; Scarlet, a master manipulator who delights in breaking people down; Felicia, a dangerously seductive woman battling a sex addiction; and Eleanor, a cold, calculating girl with a desire to watch the world burn. As Holo works to bring out their humanity, the girls become obsessively devoted to him, their love transforming into something darker.

Civilizations change and the era restarts.

The world returned to the age of steel and steam is full of chaos, madness, twist and evil.

Among them, a group of sorcerers called truth followers have done all their bad things.

They sacrificed to evil gods, besieged the Pope, assassinated the emperor, and even provoked the First World War…

All of this had nothing to do with the transmigrator Melon. When the world was in turmoil, he was the one who squatted aside and watched the show.

Until one day, this group of people came to him and insisted on recognizing him as the leader, and also said that he was the son of destiny. Everything they did before was because they followed his instructions…

- Description from novelbuddy

He—an enigmatic and cold-blooded soldier with a mysterious background.
She—a ruthless and bloodthirsty spy.