looking for this manga

i think it was a manga or a manhwa. it was like an apocalyptic thing? i think. i don't remember if there were zombies. the setting was in a school, and the drawing style focused more on scenery rather than on the characters. i think it might include androids/robots(?) and they may not be on the main characters' side. there might be pods. i believe these are androids, they may be characters wearing machinery, but i'm pretty sure they were androids who would attack humanity (i think). also there are multiple perspectives, i believe, of connected main characters who i think are all students. it's a pretty "realistic" approach (lots of confusion, weaponry, i don't THINK there is any regression/foresight but i can't remember). i think there was a girl character who was also good at fighting.

i read this like, maybe 4-6 years ago. i don't think there was very vibrant colors, if any at all. at the time it only had around 30ish chapters i think, and it didn't garner lots of attention.

it's not deadlife or zomgan.