The Warden of The Witches - Chapter 6:

Kusumi Chiharu gets a message one day that he has been selected as a Monster Tamer, and he is prompted to select his first partner. He thinks little of the message until he receives a giant package the following day. He assumes it’s the porn books he ordered, but the huge box ends up containing the unconscious body of a near-naked girl! She’s a ghoul named Zonmi, who intends to fight beside him as his partner.

However, it turns out that other hot girls at his mostly-male high school are also magical entities, and Zonmi may not be the only one who wants to fight by his side!

Read at least six chapters, then prepare to crave the rest.The main character will show up in Chapter Five, though I don't recommend skipping the first four chapters.-----The world was celebrating. The Demon King was dead, along with his Darkness Generals.Humans led the other races to war for subjugation. They killed all, and none were spared. However, thousands of years before this happened, a piece of history was altered by time itself. In fact, the Demon King didn't have four generals but only one, which he sealed and sent into eternal slumber. Just as he started to close his eyes, the chains locked away for eternity shattered into pieces.

A polite and lethargic boy was reincarnated in another world as a vampire bishoujo.

The meteor pierced the sky and also pierced the peace of the world.

Transcendent power comes to the world, who is watching in the dark, and who is whispering in my ear.

When the roar shatters the sky, when the power steps down the abyss, when all life and death are dominated… They call me – God.

- Description from novelbuddy