The Tale of Crimson King

This will be my first novel that I had ever written so there can be some mistakes in my grammar so, you can ignore them or inform me so I could improve on those points.
This story began from the summoning of our MC from Abyss by the Demon King to fight against the Hero. The MC that is summoned by the Demon King is someone who knows the Hero and is very familiar with one of the members of his party. But the Hero and his party were summoned from a modern world and MC is summoned from the Abyss which said to be even more worst place than a Hell. Just what happened to MC? Why was he in the Abyss? And will he help the Demon King or will he join the Hero and his party? Find it out all in this novel!
As this story progress, I might add other tags like romance or maybe even harem. For now enjoy!