I didn't like this chapter. We already knew the backstory of Minami and Shizuku from previous chapters - they bonded because they were both abused as kids, and used one another as replacement family. All they knew of family was violence, so it wasn't a healthy relationship, but it was one I could feel sympathy for. Adding this outlandish backstory makes Shizuku harder to connect with since the details are so strange. Maybe if the author had set up the specifics ahead of time, it would have worked better. But as is, Shizuku dumps the whole story in one page and moves on. So I mostly felt confused, not sympathetic.
The frustrating part is that I don't even think Shizuku's backstory is going to matter in future chapters. Based on the volume 2 cover I assume Shizuku/Saori are going to be more of a focus in upcoming chapters, so I think the purpose of this chapter was to establish that Shizuku misses her pseudo-sister Minami, and is jealous of Iori. Maybe that will lead to further conflict with Minami. Maybe Shizuku will work with Saori to undermine Minami/Iori; they both seem jealous of their sister's relationship. Maybe all of this was pointless, and the next several chapters will be Iori/Minami fluff. Regardless I don't think the specifics of Shizuku's backstory will come up, so the author shouldn't have randomly included it.