Ah ..... reading this without knowing beforehand, the familiar scene made me stifled.
I really don't know what this author wants to give. There is nothing new, except for the characters and the concept of justice is slightly simplified. Without going further, the psychological battle of human selfishness will all be repeated, over and over again.
Wait for a minute if this prequel to Jisatsou would it mean the bad ending?
Because no one survived in the island except one man when the MC group arrived.
But the guy that gave him the dog went into the mountains early on when some of the prisoners were still alive, so maybe one or two escape the island successfully?
when the veteran dweller talks with Sei, he mentioned that he had already helped a couple before, perhaps referring to the MC for Muhoutou. Said couple were mentioned to have come escaped from an island from southeast Asia, if I remember correctly.
That information can be verified in chapter
165, page 12(the translator even left a note ranting on that), and chapter 167, page 19. It is highly likely that they are referring to the same couple.
Maybe that the guy with dark hair who's with the MC might be the veteran dweller, but that's just a guess from what we currently have