Correction:
*on WHY is the LOOP happening, it just showed WHAT (the loop) could be happening
There are hints that the zombie thingy is virus related but this does not have any connection really to the MCs. Brown hair is business major and black hair is an art major, none of them are science major so the likelihood of "guilt for causing the virus outbreak" as time loop cause is low.
Also, what is curious is that Black hair has major in ceramic yet he took classes not related to it? [Not normal in most schools in my country, is that normal to others?
I think I love you, please keep this comment updated and edited.
Loving your analysis on the story. There is a story similar in concept of the never ending loop where the loop restarts if one of them dies. It’s called my reason to die.
I saw someone else mention that ml has scars all over his body despite not getting too injuried in this timeline. Maybe that has to do with past timelines where he did get killed first?
A dead man switch is a safety device for the machine to know if its user still has the capacity or alert enough to use the machine. For example, in trains, a driver might need to hold the dead man switch in the form of a handle all throughout the ride. If they lose their grip, the emergency breaks activates.
If we apply this concept to our characters - black guy could be the dead man switch that will kill off brown haired guy if he acts wrong like when he said that if brown haired guy wants to die, then he'll kim himself.
So, if this is the case, brown hair is the driver and black hair is the machine.
What is the connection of the title to the MCs and to the loop? I don't know.
We still don't have enough clues on why the loop happens, why is it always in Christmas day, and why does brown hair triggers it?
If we go back to Christmas day, brown hair wakes up after getting his well rested sleep after his business strategy theory class final report which he worked on for 10 days and with 3 days of that having almost no sleep. The only thing hinting to zombies and brown hair is his nightmare with his professor.
On christmas eve, black hair had a party for bday. He went back to his dorm that night without his friends, slept for a bit and woke up on Christmas with his friend turn to a zombie.
No hints even in season 1 on WHY is it happening, it just showed WHAT could possibly be happening. Or maybe, I just missed some details.
So... there might not be any connection behind the title and why is brown hair causing the loop.