Avoid Yandere Constellation - Chapter 12: Legitimate Business (3)

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.

Year 2056, in a city in the Yuan Jiang Su Jin area. On top of a ruined, shattered six story residential apartment sits a teenager wearing a combat vest, militaristic trousers, and alloyed battle boots. On his back is a hexagonal shield and equipped is a blood-shadow battle knife. He sits there silently on the edge of the roof. At this time, the sparkling sky was shining and there was a refreshing breath within the air that blew towards him. However, there was only silence within the ruined, deserted city, with an occasional howl that makes your heart skip a beat.

- Description from novelupdates

Vincent Strider was a gun for hire who made a living by killing whoever it was his clients wanted dead. But during one mission, he died in a fierce gunfight. However, death was not the end for him. Vincent found himself reincarnated in another world, facing a floating interface that flickered before his eyes.[Synchronizing Host!][Military System initializing.]Vincent found out that in this system he received, he can summon soldiers, tanks, aircrafts, and even warships! This is going to be exhilarating.

Roy’s life was nothing special. The only thing commendable was the last few moments when he saved a mother and her child from a drunk driver.
…
It’s really an egg! Damn it, what kind of monster have I become? Did I fall into Hell instead of making it to Heaven??
Join Roy as he ventures through various worlds with the Custom Made Demon King System—a system that allows Roy to draw anything he can imagine and create it through exchanging souls!