Z/X: Ignition
The story is put in the not-so-distant long run. Five"Black Points" unexpectedly appeared across the world as portals to parallel worlds. Instantly after critters began their intrusion. These critters are the people of five worlds--the same worlds in different time frames. In order to make certain their own interval succeeds, the five invasion forces each battle to wipe out one other time frames. The key would be just one unit.