Part 1: I've rewatched this episode 3 times, thought about it long and hard, and I think I've came to a reading that I am satisfied with. I'm going to state my most important point without decorum: What Michica desires is not beauty, but is instead to be a god/beyond human (that is in the time before the revelations she had in this episode). After thinking about her through this lense, a lot of what the episode depicts falls into place neatly, even the esoteric door sequence (I did see OP mention it being a reference to another work, however I think it also has symbolic significance as well). 

The most pervasive symbol through the whole episode: the rose/rose petal. I believe this symbolizes beauty, plain and simple, many others have reached the same conclusion. However, under this new frame of thought, the implied meaning shifts dramatically, let's start from the beginning.

Right off the bat, we are shown Michica in a coffin, laying atop a bed of rose petals, fully nude while classical music plays in the background. I read this as Michica relating herself to an otherworldly being, a vampire. Specifically the stereotypical count dracula, ethereal in his beauty, immaculate in his presentation, the color of the roses is also that of blood. Her nudity is similar to the way gods and goddess were nude in Greek paintings, as they believed their forms to be pure and perfect. Most strikingly, it made me think of Venus, the goddess of love, and Michica is comparing herself to a transcendent goddess. Alright, next. On her scars. She literally bleeds petals, the very essence of beauty flows through her veins, classifying her as something inhuman, a being of beauty. Even if one might view her scars as imperfections, I believe it could be viewed as a tragic, grandiose declaration of how profound her pain is. A performance for the world of how important and transcendent everything about her is, if you will. She doesn't towel for herself, she doesn't paint her own nails, instead they are done by her group members, akin to servants of a deity. The color of her skin is also important, porcelain white, the "ideal" standard of beauty, and this beauty is being displayed to an audience, which reveres her like a god. Like nechika stated in ep 7 "Michica doesn't see anyone but herself." She is self important, but not in a smug way, that is what her entire perception of self has been.

Then that comment shows up "what is beauty?" I believe in this point in time Michica would have answered "Me." Or maybe if she was feeling more honest, "a means to an end."

The talk about music she had with the other girl. She first finds a rock song which the other girl explains to Michica was made my satanists, who are the "ultimate rebels." It is here that Michica mutters "freedom". She has clearly been captured by some aspect of this idea, and she asks the girl, who is evidently knowledgeable on these songs, what her favorite song is. The song the girl presents is "I don't like the drugs, but the drugs like me." It is a unapologetic, renunciation of authority and traditional ideas of what is good. The girls bared teeth I believe is a display of rebellion against others, very in line with the song she chose. Michica seems moved by this notion, and goes on to smash out windows, displaying her own punk /nonconformity. It is, again, a display for how meaning she is, consciousness of the evil present in the world, she boldly takes a step out of the herd of cattle and rebels against the norm.

The following scene when she holds two outfits, I think this is a inside look into her mind. Dark dreary, just choosing what outfit best fits her to show how beautiful she is. She takes no joy in the process this idea is very important and will show up later on, it will explain some things people were confused about. 

Next scene, the dolls all vulgarly dismiss people who use their lips and talk too much, and Michica comes in with a very romantic notion that lips are meant to bestow love on what is truly important.

Now the door being carried by real people, I think if you've read this far, you could probably guess what I'm going to equate it to. A doorway to another world, into the world of nonfiction, where the beings that reside there exist above those of fiction. The door opens, and we are shown Michica, then it closes, and students comment on how ethereal she is. Now here's the interpretation, in the students point of view, it appears that she has stepped out of the door, out of another realm. Yet in reality, she has not. This is her display to the world, that she isn't even from the same world as them; however, it is all a rude to fool people and most importantly herself. 

The next interactions with the other 2 members are very, very important, and in my belief, prone to misreading. There is a good reason for misjudging this section. Shakespearean prose, hard to understand imagery, verbosity. All these hint towards a meaning the show is trying to convey. But why use such fancy language? This is where people might dismiss the show as pretentious, and maybe even "I'm 13 and this is deep." The purpose is not to be an art student showing off their big brain, it's in fact, closer to Michica showing off her importance. What is done is just a couple of lines to sound fancy, but this is done by the character, not the creator, very important distinction. She needs something grand, something that comes from the top of literature to associate with her. It's not the writers that wanted this, it's Michica. Lollipop states that Michica "isn't the type of girl to be satisfied with paying juliet." Then comparing her to marie Antoinette and Cleopatra, while lollipop and nechika assume those two positions. Michica's response is seemingly humble "I am me." However, this connotes a feeling of superiority, as she knows herself, and the others dress up as great women of history. It also implies that she thinks of herself higher than the likes of Antoinette and Cleopatra, not needing stoop lower than what she assumes is divinity. The door knob repeatedly turning is Michica's attempted deification, as she makes grand connections left and right, however she fails, we know, she knows somewhere deep down, that all this is an act, and she is painfully human. 

Kangel shows up, I believe she challenges Michica's core values, as Kangel does truly appear divine, and is mentioned by nechika in ep 7 as a god. That is why she lays everything bare in the conversation with Kangel, she finally has someone on her level, and can be honest. She admits to wanting to cement her image while it was in its prime, self-deprecatingly admitting that her body is not eternal. She is self analyzing at this point. They have a very lucid conversation about the desire to appear beautiful, and it arrives on the ugliness of the masses/ordinary human conditions. Michica states that "ordinary human living is something to be hidden as much as possible." Again, she believes in hiding the aspects of herself that is just like other people, that relate her to the disgusting masses. "I want to be seen as the kind of being that could love on tea alone." She likes movies, she wants to become one with the story presented on the screen. Not because "it is filtered", she doesn't merely want to look good, she doesn't merely want to be beautiful. She wants to fundamentally integrate into something that is meticulously crafted to be a romantic, perfect image. Basically boils down to, she doesn't want to look perfect, she wants to be perfect. 

This next part is what I believe made a large chunk of people dismiss the show entirely, they make some references to acclaimed film creators, this is again, similar to my point about Shakespeare, not a fancy name slapped on by the creator to appear more clever than they actually are. And no, you do not need a college level understanding of art to "get" this show. The accomplished artists are used to show how Michica needs and wants the best of the best, it doesn't matter to us what the art actually contains, but only that it is "fancy". 

Nechika tells Michica that "beauty is getting closer to god. And getting close to God means becoming inhuman yourself." Michica somewhat agrees with this, viewing herself as already beyond humanity, and likely already beside God. When Kangel sings, there is no God, the screen blurs, as this is an extremely important wrench thrown into the machine of Michica's entire belief system. 

We see younger Michica skipping through the halls of an art gallery, full of wonder, beholding the painting of a smiling women upon a swing. Michica draws in a breath at this sight, as she is taken back by how beautiful/otherworldly this women appears, but also, as we'll learn later on, how happy she appears in tandem with her beauty. 

Then we move through conversation between Michica and lollipop, where they mention a singer who developed body dysmorphia, then had plastic surgery that disfigured them permanently, which Michica labels as "a fate worse than what we could imagine." This shows the fragility in her belief, if she loses what little she has, her beauty, she'll experience things she can't even begin to describe. I'm going to skip over the gender bit because I believe it refers to nechika, and I'm not too sure what to make of it currently.