apologies i sent that reply without checking the spoiler tab and now I do have some suggestions ^^
it seems your story above is a mix of outline/narrative. both seem to switch very quickly
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"When Raiya turned seven years old, he had no friends due to his behavior which is different from normal children of his age. He can't make any facial expression and he doesn't really care about it. He hated going to school because school to him is just useless as the academics inside schools are inferior, he runs and exercises a lot to gain stamina and maintain his health, and is satisfied with what he does. One more reason is that, he decided to keep his skills a secret. So, he started to live without any contact to the outer society. Mirai often gets in quarrel with him as she feels envious as he is an unimaginable genius but she is a complete idiot when it comes to academics. She shouts "Why this boring brother got such a gift while I didn't get such skills??" every time the quarrel ends"
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this here is a key example, for one bit you skim the story briefing us on Raiya personality then come to a sudden halt when the actual story comes into play
it makes the story very hard to follow and extremely jarring. Although i can tell you have a lot of ideas and judging by the pace and style you want to get to the meat of the story ASAP, which I and many others here can relate to
but the job of a writer is to pace our work and give details that allow the reader to visualize your story and become a part of it
here is a example
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Inside the research laboratory:
"God, a success after a long time." the assistant scientist says with a relieving look in the face.
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be it a script for someone to draw or a novel its still important to give us a little context then just "research laboratory"
so here would be a basic example, although I recommend not following my example exactly since novel format is not my forte, its just to give a idea ^^
the smell of chemicals hung in the air as an excited scientist paced around the edges of his laboratory. the room was packed with machines and beakers each filled with unknown liquids and experiments
this small example gives your readers a layout of the area, allowing them to settle in and witness where the story takes place
a decent way to start (till you find your own rythem) is to describe the area any time the location changes, especially if the characters preform any actions or dialogue
this next bit is subjective to my own preference, so do keep that in mind
but i find part where the story drops exposition of a character to be rather distracting
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When Raiya turned seven years old, he had no friends due to his behavior which is different from normal children of his age. He can't make any facial expression and he doesn't really care about it. He hated going to school because school to him is just useless as the academics inside schools are inferior, he runs and exercises a lot to gain stamina and maintain his health, and is satisfied with what he does.
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im sure you have heard of the saying
"show don't tell"
instead of dropping this exposition onto the reader, you could instead show it
set up a location of Raiya being alone being either mean or perhaps avoidant of people
then perhaps someone tries to talk/be very nice to him and Raiya does not know what to do and the person gets angry/annoyed/both
or something
then we can get the idea that Raiya has trouble making friends and during the story we see he cannot make any facial expressions and learn that he is unable too
but if you must get that stuff down quickly then it might help if someone is talking about Raiya to another person perhaps a teacher? or someone of note?
that way the description above can be given more organically
so on and so forth
and finally it would help to figure what kind of Narrative structure you want for the story
1st person. when we are in the head of a single character hearing their thoughts while others around them are a mystery
ever read goosebumps by R.L Stine? or any book that focuses on the words "I" and "me" or "we"
3rd person. when we focus on multiple characters, which you can dive into each of their minds and read out their thoughts or just ones you select
harry potter is a good example of this style or any book that focuses on the words "he," "she," "it," or "they"
and that's about it for suggestions if you have any questions or if you need me to clear up something let me know ^^
-Action