MTL - Machine Storm - Chapter 11 I study financial management

Kurokawa Risa is an ordinary office worker, who has practiced lots of cooking while living alone. One day, she wakes up in another world, with a concerned little spirit hovering over her! She has apparently been transported to a magical, spirit-filled realm by the will of the goddess, and there is no known way for her to go back. She is taken in by a wealthy couple, and they and her new spirit helper treat her with nothing but kindness. There is one problem, however–the food in this magical world is gross! Risa insists on helping the household cooking staff prepare a traditional meal from her world, and it is a big hit with her hosts. Soon Risa knows what she should do in this new world; she should open a cafe and treat everyone to delicious food!

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.

Then placed into a high-school setting, Lin Yi is tasked by the chairman of a top-tier multi-billion company with bodyguard duty for non-other than his own daughter, a certain little Miss of said high-school.

His enemies, once ranging from drug lords, mafia bosses, political figures, and national leaders, are soon replaced with spoiled kids who happen to have rich papas and mamas, and Lin Yi finds his intense expertise and high-threat skillset misused, and very underwhelmed…

But he does get a harem cast as diverse as his old enemies, so Lin Yi decides that, for the sake of messing around with girls as an invincible entity in a down-leveled environment, leaving his bloody and death-filled war days behind is something he’d definitely want to strive for.

- Description from Novelupdates

After the nuclear warfare, massacres started to spread throughout the entire world. The order between humans completely collapses, and the strong eats while the weak gets eaten becomes the #1 rule.

There’s a legendary Bishoujo Game that has become popular among Japanese gentlemen.