(Dig a pit, scoop some soil, bury it, count one, two, three, four, five—look at my pit-digging skills! I've held back for over a thousand chapters without mentioning this soldier's pit... Also, looking for monthly votes at the start of the month.)
The entity that trapped the Revenge Army in the Otherworld—whether it was a program or a supreme directive—acted like a barrier, protecting Sandora and her soldiers from the cataclysmic disaster of the Old Empire.
So we ultimately decided to call it the "Unknown Barrier Effect," or simply "Barrier."
