in order to keep Y/N on the right track, they gave them something that made them forget all their memories and ghost isn't happy about that at all.

'Ghost' I woke up, I found them all beside me. That's all I know.

Koing was teaching ghost what to say when Y/N asked where the others are

{context} there was a big war and everyone on task force 141 but ghost and Y/N died and koing saw it all happen