Hell Heaven Secret Agency

100 years ago, the world merged into one, the world of humans, demons, angels, and beasts. But in this world, humans have more advantages as their technology is rising rapidly. The other beings are demon populations on the verge of extinction as the alliance of humans, angels, and the beast constantly hunts them. The demon lord was weak, and he commands the high and greater demons to infiltrate and breed with humans to increase their numbers. The dark angels and savage beast joined and to create a massive army of halfbreed humans. To destroy the alliances. The plan was successful, and they made a secret group known only in the underworld called Heaven Hell Secret Agency. A group that helps other races not limited to demons survive this rash world and slaughter the greedy human official who keeps controlling other races to dominate the world.