This article is my OC story, mainly written for myself...)
The world view is relatively large, and there are many characters, but they almost revolve around the male and female protagonists, so it's OK to remember them (? You)
Pure alien demon and human experimental subject x frail and sick human girl + BG body type age difference love + mutual redemption of family love and more
The characters in this article are almost all pure humanoids, there is no such thing as humanoid (they just don't want to change). A few are humanoid, but only in semi-humanoid form.
Intention: What is this?