At what point does horror turn into terror? Or dread into despair?

Already you may be thinking of endless ways to interpret this question. From the perspective of Getsurin: The answer is time. The durations, the endurance, the consistent thought of when will this end.
Not knowing is what makes terror real, and what spreads despair. The unknown for what the future holds creates these sensations, the primordial instinct to fight, but the modern mind gazes at nothing, becoming frozen at the awe of the unknown.

For Getsurin, the rest of his life is just a few months away, the unknown of the future is ready for him. However, the terror of the unknown does not revel in consistency. It wants to bring an experience that not one soul could ever prepare for.

The despair and terror of the unknown has found a new perspective for Getsurin. One that will begin with seeing something sinister.