“For generations, the world has been protected from the evil monsters and beings of darkness by a mysterious guild of heroes called the Celestial Guardians. People gifted with the powers of animal constellations. They have the ability to transform into their specific animal, as well as possess amazing powers of their own.
Every generation, twelve special beings are chosen to inherit these abilities for the greater good. But for this current generation of chosen ones, a brand new guardian is selected to join them. This story follows a girl named Sakura, as she and her newfound friends work together to defeat evil and become the Shining Celestial Guardians.”
Your description is way too wordy. My rule of thumb: Don’t tell what can be shown unless it’s absolutely crucial you understand it before entering the story. You’ve got a good idea going on, but imagine you’ve started a back alley snake shop. Your snakes may be world class, but you don’t have a lot to work with to advertise them, no fancy signs etc, so it’s up to you to sell your snakes with words.
Words are all you have, so ask yourself, if someone were to read this, what would get them hungry and encourage them to invest their time in your work? The description is the window the reader has into the novel to determine whether or not they want to continue reading it or not.
Here's my take on it:
“For generations, celestial guardians protected the world from beings of darkness. Gifted by the power of constellations, each guardian can transform into their own animal, giving them powers of their own. Sakura is selected to join them. Can she rise to defeat evil and become a celestial guardian?”
A good old call to action typically helps bring urgency and curiosity. Set up a problem, the answer is in the novel.
“Stars… there are billions of them scattered across the night sky, sparkling like a sea of diamonds. No one truly knows how they came to be. All they knew was that they existed for millions of years, spinning around the world, in a never ending cycle. They were a mystery, yet also a miracle”
Your description of the stars is beautiful, as well as the general opening sentence. You did a good job, especially when you say ‘sparkling like a sea of diamonds’. It gives such a gorgeous mental image! I applaud you!
This paragraph, however, can be elevated. Before I go in depth, I want you to reread what you wrote right now and ask yourself what can be cut and think about it. Afterward, I’d like you to continue the comment.
There are billions of stars in the sky. That’s basic knowledge we don’t need to be retold. When you say ‘all they knew was that they existed for millions of years’ then ‘they were a mystery, yet also a miracle’, putting those sentences side by side, isn’t it redundant? You’ve already implied people don’t know much, so on their own, your reader can interpret they’re a mystery.
Avoid over-telling. Your reader is intelligent and can figure it out.
“Stars shimmered across the night sky like a sea of diamonds, how they came to be? No one knew, but they’d seen humanity from birth and maybe to the end.”
In my suggestion, it’s essentially: you don’t know the stars but they know you, giving them that billion year old feel, like something beyond human understanding. But to match the sea of diamonds, I try to make them feel gentle and more like they’re watching over instead of just watching, haha.

The theme constellations have for your story is pleasant. It really gives the holy-holy celestial feel, very pretty. I’d suggest though, that you could rework “Within the stars, constellations formed the shapes of creatures and many of beings. A large number of these constellations had formed animals.” into something shorter. Such as:
“Constellations filled the stars”
It’s vague. You have room to explore us more throughout the story. It can be shown to us instead of said, but such an important plot point has been put emphasis on enough.
You don’t need to tell us they’re more intriguing, you can also show us that throughout the story. In the beginning, set it up with someone telling the tales, which was already a great head start for us to realize this. So instead of saying: Animals were the most intriguing, I’d suggest re-framing it like this.
“From lullabies to campfires, tales of animal constellations soared.”
Language is your tool, use it. I used soared, which gives the reader a sense of enthusiasm, like these are at an all time high. When I tell you a lot of us know ‘Ring around the rosy’, it may give you the feeling it’s culturally ingrained. Since it’s in lullabies, people consider it important enough to tell their kids. Then to campfires gives it to idea it’s remembered across ages.
(If you’re not familiar with it, it’s a very popular song among American children, I still remember it word for word haha)
But if you don’t feel completely right about it, that’s okay too, you can just add, “for as long as the stars watched over humanity”, and so on. But whatever you can explore more in depth later that doesn’t absolutely need to be immediately said, save it for when you can because excessive telling clogs up your narrative and may bore the reader.
Think of it like water, food and sugar. Water’s your story, food is your novel. You can sprinkle sugar into said food to amplify the taste you want.
This rule can also be applied for the rest of the prologue. A lot of it can be cut and shown throughout the story. As well as the next chapters, like you saying she has a loving supporting mother, that can be shown.
The story of the animals can even be shown by someone telling it. Envision people talking of old legends. Maybe in the main character’s research they can find old documents or it can be passed down from their teacher, or you can show it in a flashback. It helps add interest without saying too much. Telling is a very common pitfall something I had the hardest time not doing.
Long orange hair and bright pink eyes feels stagnant for a description and not memorable. This is our main character. You want her to be memorable to the audience, right? Then I suggest you give us a good mental image of her.
There’s a lot of cases where you don’t even need to describe the main character all that well and just drop hints as to what they look like throughout the novel, as long as their personality is strong enough to stick with the reader. In one of Jane Austen’s novels the only thing she states about the main character is about her eyes.
But we’re also looking through Sakura’s perspective, so add a bit of character to her self description too. How does she see herself and the world around her? I’d also suggest you work more on scenery descriptions.
Here’s a couple techniques I know that will help you with descriptions if you choose to use them! Comparisons: “His teeth were white as paper” helps put an image in the reader’s head and mini stories: “The knives her her glare could shoot down any unlucky passerby” which helps to get the point across while making everything feel more vibrant.
I noticed you also have a tendency to repeat things, like “I saw” etc after “I peered inside” I’d cut the first.
You did kick off the plot early, which was great! I liked it! You’ve got a lot of creativity going for you and none of this I say to bash you, but instead, I want you to take it and use it to elevate your work! You’re already doing good by just putting it out there for people to read, which takes a lot of courage to do. Good luck and happy writing!