Third person POV\
[1 week later…]
Reina was now finished making something in the lab. Gen was busy researching for the cure in a separate lab. Reina had made a serum and replicated it with his Template Serum, which can replicate any liquid serum. He made the serum, which he had called Almost to the Brink of Death. True to its name, that serum didn't allow him to die in any way. The recipe and formula for it are kept as a secret by him in his spiral-bound notebook.
For the past 1 week, he had tested his previous batches of the nerve-freezing serum on lab rats.
He remembered he at least sent 3 of them to death and 2 survived.
So after that, Reina wanted to test it out by injecting it into himself and find a deadly situation to die in to test its effectiveness and efficacy. These were driven by his desire to cleanse himself psychologically of his sins.
So, as a Roman Catholic, he did the sign of the cross before injecting the freezing serum into his mouth. Gen doesn't know what he was doing now. After that, Reina grabbed his spiral-bound notebook and read an entry that compares his dread with that of Kirito Kirigaya after Eugeo died.
It said:
"I still remembered how Kirito look after his amigo Eugeo died. Those hollow eyes…Yeah, sí, I admitted I looked like him, yet I did not let my dread and depression consume me. I had my own goals for this outbreak.
I was quite mysterious when I made a million distinctions on the psychology of my own mind, like a Calvinist or a Lutheran doing scholastic theology."
After that, he wore his red and grey camouflage gear of Gen's organization and went out to find a deadly situation to die in to test the serum's effectiveness, going with a squad led by Nato. Nato never questioned why he suddenly decided to join in.