- Myne is a very young girl, so it's entirely possible for Liz to have died before she was born.
- There may be a much deeper reason Myne feels like giving Benno a gesture of comfort the first time she hears of his fiancée.
- Otto's "Goddess of Water" prank (which basically consists of suggesting that Myne is Benno's lover) could be a very weird sort of Joke and Receive.
- In a chapter from his point of view, Mark remarks Benno's interactions with Myne greatly resemble those he had with Liz.
- Per the author, Liz had the Devouring also, just a case mild enough that it didn't kill her before her mid-teens.
- The evil stepsister is neither evil nor step, but is the kindest person around and Cool Big Sis to Myne.
- Cinderella being forced to clean and cook for her family - Myne cleans and cooks of her own free will, to improve her living conditions. She cleans so much that everybody calls her clean freak. She cooks and teaches others to cook to improve the taste and spread the good food around.
- Cinderella sleeping among ashes and soot and so gaining her nickname, because she is always dirty - Myne especially focuses on cleaning the bedroom (its even one of the weird things Effa remembers her by!), collects soot so she can make a pencil for herself and ash from the chimneys so she can make ink. And she invents shampoo as another inversion of Cinderella being dirty.
- Cinderella being recognized due to her foot being the only one which can fit into a magical shoe - Myne herself is magical and high quality magic tools shrink or stretch to fit their wearer if infused with mana. And Myne gets recognized because of her abilities, not her looks.
- The prince finds her during a ball he organizes to find a wife for himself and falls in love - There are two people playing the role of a prince: Benno and Ferdinand. Benno is a lifelong bachelor, he finds Myne because of an event/meeting SHE organized and falls in (fatherly) love with her because of her abilities, calculation skills, ability to learn, endless ideas and a sharp mind. He himself is not a heir of a (business) empire, but rather a regent until Corinna comes of age, marries and has a child. On the other side, we have Ferdinand who IS a son of previous Archduke. But he is the youngest son of a mistress, is not in the line of succession and meets Myne during her baptism, an event he doesn't organize. Ferdinand is also very much NOT looking for love or wife but takes a liking to Myne anyway, for the same reasons as Benno.
- Cinderella is poor until she marries a prince - Myne first gets rich by her own actions then gets many attendants over the course of the story.
- Cinderella is a commoner who marries into nobility - Myne is also a commoner, but she is first transformed into a daughter of arch-noble with a few lies and magical contracts then adopted into archduke's family. So she does become nobility, but through lies and adoption, not marriage.
- The prince falls in love with Cinderella during a dance with her - Ferdinand teaches Myne how to play a musical instrument and she teaches him a few new songs but there is no dancing.
Rosemyne didn't really break her feystone. It just took the form of explosion or popped balloon that she imagined. Feystones break when you put too much mana into them and it was demonstrated multiple times, but that is not what Rosemyne did. She poured a little mana but imagined it exploding. Then cut off the flow of mana in surprise, so it stayed that way. When she poured more mana and imagined the feystone taking the form of putty/dirt, she was just changing its form like usual. The reason Ferdinand didn't recognize it is because nobody sane would imagine their feystone popping like a helium balloon, not the least because there are no balloons in the world.
A side story in Volume 1 of Part 1 (not adapted into the anime) shows the commoner children hunting shumils while Myne is sick. While butchering them, the children have to avoid hitting the mana crystal inside their bodies, or else the entire body is lost. This happens to two of the shumils, and the children butchering them end up taking the crystals to a store to sell them.
In Volume 1 of Part 3, Karstedt spells out that the feystones on which Nobles rely to do magic and make mana-absorbing tools are the crystallized hearts of dead feybeasts. Combined with the scene above, this indicates that while Nobles may have a monopoly on the means to make magic tools, feystones themselves, especially those from smaller feybeasts, really aren’t that hard for people to get their hands on. While the Devouring patients shown in the story actually do need proper magic tools, small feystones may be a sustainable solution for a Devouring patient with low excess mana. Myne herself never discovers this during her commoner life because she never actually holds a feystone “fresh from its source” and only ever encounters another cheap solution, taue fruits, which have the drawback of becoming trombes once they absorb mana.
It’s entirely possible someone did discover those solutions at an earlier point in the setting’s history. Taue fruits were simply not used because of their drawbacks, and magic tools were born out of efforts to make feystones more efficient at absorbing mana and/or networking them so more mana could be absorbed at a time. For a while, there was a long-term positive feedback loop of better tools letting people with more mana reach more advanced ages and those people being able to make tools better than those that had kept them alive. Somewhere along the way, someone realized that it was to the magic users' advantage to convince commoners that only magic tools made by Nobles could cure the Devouring, and that "raw" feystones and taue fruits were completely worthless items. Meanwhile, they made sure Noble children never came into contact with those items, and that no adult Nobles would come into contact with Devouring-afflicted commoners before all but the mildest cases (e.g. those with very little mana) were dead anyway. Thus the whole "you’re not legally a human being until you turn seven" rule, that concretely results in Nobles never meeting children that aren’t part of their own family before they turn seven, the age before which the vast majority of Devouring-afflicted children are known to die. That is, unless someone in the child's family happens to have enough connections to nobles to get them help.
There is another detail about the setting that hints someone with some sort of authority could have known the link between taue fruits and trombe at some point: the lower city's Star Festival encourages commoners to remove a bunch of taue fruits from the forest and promptly destroy them, all-too conveniently greatly reducing the number of taue fruits that can potentially meet the conditions to become a full-grown trombe in the process.
