I don't post, im more of a lurker around these parts, but this manga has made me just want to say what i think.
The heart of the earth, alright, so heroes appeared because of the earth maybe unnie is the representation of such heart. The unknown person that transformed koishikawa had marks around their nose that reminded me of craters like those in the moon, so my bet it that this one represents the heart of the moon, and on top of that the dark side of the moon, kinda fits the theme.
Wild theory seeing how its only 2 chapters in but my 2 cents are in the basket for now, this manga seems that is gonna be quite interesting, yuri or not.