Demonic Dragon: Harem System - Chapter 345: Competition (R-18)

Though he received the skills necessary to teleport across worlds, the king who performed the summoning ritual attempted to trick him into wearing a slavery collar, this annoyed him so he kidnapped the princess and returned to Earth.

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.

“What, how the hell did I get here?” Vorden a normal 20 year old guy in an urban world gets trapped in a video game. He goes through trying times, life and death battles in the hope that he can find his mom. Don't miss out on the most eventful Urban Fantasy story with twists and turns, with friends and foes, and with love and hate.

In the year 1368, at the end of July, deep crimson shall descend from the heavens.

- Description from Novelupdates