Isekai Maou to Shoukan Shoujo Dorei Majutsu - Volume 5 Chapter 6 part4

When an S-class elite assassin-raised captain of a special ops suicide squad comes home from a high-stakes Africa mission, he finds himself offered something that could potentially set him up for life- a curious assignment that he could use to finally exit his days of war and slaughter.

Ruel finds himself thrust into a brutal post-apocalyptic world, bound to a bizarre “Milf System.” This system demands morally questionable acts – NTR, seducing milfs, and claiming other men's wives – as the sole means of gaining strength and essential survival skills.The brutal reality of this new world awakens Ruel's hidden lust and dark desires. He swiftly abandons any semblance of morality, embracing the system's perverse demands with growing fervor.Driven by an insatiable hunger for power and pleasure, Ruel revels in the ravages he inflicts, using his newfound abilities to dominate and conquer.His journey transforms him into a ruthless force, where survival is intertwined with the satisfaction of his darkest urges, leaving a trail of broken relationships and conquered women in his wake.

Being poor, weak and introvert, Daniel Lolzwood has always struggled to get a friend, let alone a girlfriend. Who would have thought that one night, a succubus, the most beautiful girl he had ever seen, would come begging him to become her boyfriend? She even gives him a strange system. He can now visit a fantasy world and...Enough with words. I guess it's time to become both rich and handsome while enjoying beauties and revenge..............................Additional tags: [No Yuri] [No NTR] [Adult Content Warning]

Her – a glutton without troubles or worries who crossed over and became a young fat chick with a deep vengefulness.

Him – a young master of the number one power; a two-faced man with elegance and charming, good looks; he is the chosen one of the former saint god and a man who will only bend his back for her alone.

This domineering crossover’s slogan is, ‘Don’t touch if it is this sister’s, put it there if it isn’t this sister’s!’

…watch how the Domineering Glutton and the Two-Faced Venerate Emperor create sparks as they meet and collide, stirring the whole Spirit Treasure Continent into turmoil, how they fall for each other and how they kill each other, how life and death severs love.

- Description from Novelupdates