Guardians of the Gate

We open with a demon curling from a gate and a grotesque monster escaping. It is almost time. The monsters are immediately killed by shadowy figures. Demons once ran amuck in this world until the guardians of the gate came to be and stop the traveling of demons into the humans world for once and for all. But the demons are now planning to reopen the gate and the once powerful guardians have weakened. Can they stop the demon invasion? Or will demons once again rule this world?