It is indeed quite long! Although I only read the first part and quickly skimmed the second part, I think I have read your intent correctly though: This is a piece that is heavily influenced by the visual novel style; I think it has very Japanese characteristics, but is not fully adapted to the webnovel format!
First, about the premise and genre: it is difficult for me to discern; Chapter 1 Part 1 moves between setting up a 'school competition' in the first half, and slice-of-life in the latter half. There is also a mention of 'heroes' in the middle, which makes me believe that it is setting up a story similar to To Aru Railgun's Festival Arc or My Hero Academia's Sports Festival Arc.
However, the author turns to a dialogue with the student council president in the latter half, paired with whispers in his own ear. I can understand the premise (it is to set up Rachel as an important character and Waguri as an enemy in the future, whispers are part of the hidden power), however it feels to me that the premise and this sequence do not connect well with each other. I would shorten the sequence and move the conflict setup to a later chapter; if this were an anime, the Waguri scene would not even take up fifteen seconds of conflict. It is a setup, and does not need to be expanded on fully in the first chapter!
If I were to change it, I would fully introduce the concept of the 'festival' through the passerby girl and internal thoughts; perhaps the girl is talking about the festival very loudly before she bumps into him. This way, important things are told and explained faster and holds audience interest better. Perhaps she is the important character called Ryûko, who did not appear in part one! This caused a disconnect between the synopsis and the first part of the chapter, because as a reader, I keep wondering: where is this going?
In general, I feel that the sequences are setting up something (Yuuki's character traits, Rachel and Waguri as characters), but the weights are too 'equally balanced', and more has to be given to the 'premise'. Perhaps a more overt explanation on how the voice in Yuuki's head connects to 'wishes' and the festival could come earlier rather than later.
I have noticed you retained the 'visual novel' formatting of having a name paired with their dialogue. The writing style also swaps to this dialogue-heavy style afterwards, and creates a great dissonance in the writing.
This is the most obvious thing you can change; most people do not expect this style of writing; while it is good as a draft for a visual novel and planning for how you imagine scenes to play out, it is difficult for someone who does not read visual novels read on. A good way to change it while helping remind yourself who is speaking is to insert a simple line indicating who spoke in the middle of three dialogues, like so:
"Today is the start of a new day!"
"(disinterested) Yeah." Yuuki looked away, pretending to be interested in the cherry blossoms outside the classroom.
"Please don't disturb the new student, Ryûko dear..."
As you can see, I didn't really need the nametags to convey who is speaking. The mannerisms and speaking style speak for themselves.
There is a saying that 'The medium makes the message', which means that different kinds of mediums (webnovels, manga, anime, visual novels alike) will ask for a different kind of writing style to fully convey the strengths of that medium. Right now, I can fully visualize how the scene would play out 'as a visual novel', a strength of the writing; but as a 'webnovel reader' it would feel very weird unless they understand where the author was coming from.
Regarding chapters being long, it is quite possible to reorder the scenes and break them up into chapters. It would involve tightening the pace and including more important details up-front rather than later. The author also has a tendency to introduce passer-bys and NPCs to flesh out a scene and the corresponding 'message', but as noted, this is rather 'heavy', and those same traits could be conveyed with lighter, faster, and easier to read scenes.
In general, scenes could be condensed to strike faster at the audience's attention; the visual novel dialogue style could be changed to a more webnovel style, these are my quick thoughts on reading your work, I hope this helps you out!