Alright. This is quite a big spoiler, but the seme is actually a regressor. He failed protecting the uke several times and died and then returned to the past with the memories still intact. The uke has to be kept alive because he's pretty much the cure for the zombie virus.
Can you spoil the "Dead man switch"?? Plz
Why that guy has so many injuries? And how he know the brown hair guy? Plzzzzz spoil it for me plzzzzz