Munruel
This pretty much confirms the mc is gonna inevitably save humanity right. I dont understand what kind of novel ends with the protag killing off all those that he fought to protect over the length of the story. Ive seen this done many times where the novel the story is based on doesnt make any sense and is crafted more to benefit the actual mc than the novel protag.
The second death is way better than the first but still, the end is wired...the hero? kill everyone including his harem as if they have no power or hidden ace and the human race depending on one person is unlogical even in the novels, what normal is the protagonist preventing the enemy from using their "nuclear weapons" and the rest of the war is left for the army.