Naturally there will also be spoilers about this story. Reminder you can read it legally for free in the Arknights official site.
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Prelude Suite: Cadenza Virtuosa is a prequel manhua about Arturia Giallo, a central character related to a few Arknights events. It's divided in two chapters, the first showing the moment she truly awakened her powers during childhood and the second focusing on her Leithanien relations.
While technically the game already talks a bit about the major events narrated in these chapters I feel like it's a very important read in order to feel them, especially since Arturia's bond with her mother is a core part of her character and something some of her Operator files focus on. But most importantly there's no such thing as "I think I've seen enough Arturia, I don't need to read more".
I hope whoever's got to the point of reading this manhua already got beyond the image of Arturia being a "purely evil irrimedable woman who does fucked up thing just for fun" that has been omnipresent in the fandom for quite sometime. While her original presentation made it very easy to mistake her for an over the top villainess, and she is an antagonist and a wanted criminal, the most important fact to keep in mind is that Arturia is sincere and actively opposes the idea of hiding your true self. When she comments about only helping people gain their freedom or really wanting to connect with and understand them it's not just some rhetoric to hide her villainy or sadism: she means it. Which among other things leads to some fun scenes in game where people keep getting the wrong idea and misunderstand how her Arts works because even the actual characters from the story are fooled by her vibes and believe she's a typical manipulative illusionist.
Personally, after her first major appearance in the event Hortus de Escapismo, and while I was still halfway through Zwillingstürme, I started to see her in a somewhat "meta" way as someone with the role and power to "force" the others' character arcs, for better or for worse, which leads her to do both good and evil depending on the kind of person she's "playing" and their circumstances (thus Amiya defining Arturia as someone whose thoughts go "beyond good and evil" in her Operator Record). She's a mirror and someone who freely embraces the torrent of emotions, and while this made her a very cool and enjoyable antagonist and narrative tool, I was still unable to really grasp "her" as a person.
Fortunately, the latter half of Zwillingstürme completely blew me away and made her one of my favorite characters, but I won't go too in depth about it as that would go beyond the scope of this review and far into spoiler territory, and would need a lot more words as I'd also have to talk about her narrative foil Federico and the overall themes of Arknights.
What I do intend to talk about is how Cadenza Virtuosa also manages to show her humanity and core facets of her character, playing a big part in why her personal arc in the game worked so well for me.
The two main relations developed in this manga are those with her mother, Luciana, and with her pupil, Kreide.
Luciana was her daughter's first "victim", and a major key connecting Arturia's over the top, dramatic, "character arc forcer" identity to the crude and harsh reality of Terra; something that makes it easier to understand why so much of her motivations, ideals, and even her personality ended up being deeply connected to people's suffering. Even her focus on experiencing chaos and emotions aren't only because she uses her Arts to "feel" (something still very important to her character mind you, just a bit more in the background in this prequel specifically), but also because she makes a deliberate effort to understand others and sees these emotions as the only meaningful things that can stand up against fate and death, which she says herself in her voice lines.
But going back to Luciana: as a diplomat in the rare safe haven of Laterano, she kept feeling more restless and powerless, knowing of the war and suffering outside the walls of the Holy City but being unable to do anything about it apart from signing documents and giving what she felt were meaningless speeches, having abandoned her former dream of being a war reporter due to the "chains" that were her job and family - which is why she strongly relates to the story she tells Arturia about the shackled giant who could have freed himself any time, but was unable to do so due his fear and the years of imprisonment having destroyed his will to even try. But an interesting thing to note is that when she listens to Arturia's performances and her deepest desires come light, she does not imagine herself as the giant, but as the hero who encourages it to take action (which is exactly Arturia's role everytime she uses her Arts on people); considering her dream to be a war reporter, and the fact that the giant she imagines wears priestly robes and has a Sankta's halo and wings, it's likely that the giant actually represents Laterano itself. This is connected to the main themes of the Guide Ahead event, which was centered about the Holy City's peace being built upon inaction and the unwillingness to risk itself in order to help people outside the Sankta. Arturia's experienced firsthand the limits of Laterano's Law and the Sankta's Empathy.
Luciana wanted to move Laterano into action with her photos, and once Arturia's music removed her restraints, she instantly left everything behind her and departed. Unfortunately, the real world isn't a children's story, and being a war reporter is an incredibly dangerous job: following her dream killed her. This is a core point of Arturia's emotional conflict, because while she keeps arguing that it's better for people to live without regrets, she actively laments the injustice of the world and that fact that none of her "victims" during Zwillingstürme should have had to die, despite none of them regretting it and most actually dying grateful to Arturia for giving them their chance. She never really accepted her mother's death, and that's the first piece building her ideals about a "strong humanity" and bringing empathy to more than just the Sankta.
Regarding how she actually intends to make it possible, well she talks about it in the game, but here this is explored through Kreide. I don't think it's a coincidence his chapter starts with Arturia "performing" a Seaborn and observing their version of "unity", which kinda opposes her own vision despite having some interesting similarity.
I can't talk too much about Kreide's character without venturing into yet another great Arknights event, Lingering Echoes, but the gist of it is that he's a really good boy who lived a terrible life, and yet was able to face it with a smile, never succumbing to his fate. Something he managed thanks to Arturia and the connection they developed through music; "music can bolster our hearts, and connect them as one". A message that, through him, later also reached Ebenholz. This is, I believe, what most represents Arturia's idea of a strong humanity, strong souls capable of inspiring each other and working together to face the horrors and injustices of Terra, her hope for an idealistic future which needs to include everyone, and something deeply connected to Arknights' themes and specifically Rhodes Island. Even she was impressed by how he managed to turn "the cruel melody" of his fate into "such a brilliant opus". Kreide's was certainly a most beautiful song.
There's still so much I haven't talked about Arturia. Her emptiness, the way she expresses herself, her approach to emotion, the way she mirrors Federico and how good their bond is, her dialogues with Amiya and the Witch King... but it would be longer than what I've written up until now and would probably be more appropriate for a proper Zwillingstürme im Herbst review (if only Arknights events were on Anilist) which I'd also have to reread if I truly wanted to write about it (also I'm not sure I'd even be able to), so yeah, I'll stop here.
TL;DR: read Cadenza Virtuosa. It explores vital aspects of Arturia's ideals and characterization, there are sweet Kreide interactions you'll never see in the main game, and it has beautiful art which among other things makes the shadows of the Witch King's followers even cooler.