Soulmates symbolize eternal love, but the time before you meet them can be unbelievably lonely especially for those who have many people aren't them. because their friends as many as they may have just aren't "the one".
He is popular, captain in the volleyball team, and a third year in advanced classes.
She in invisible, watching but never doing, until she saw him. then she wanted to do something for him, to help in the only way she could. even if he wasn't her soulmate, she wasn't afraid of him.
A cliche line and a wish will bring the two together.
*I don't own haikyuu, kuroo or any of the other characters or the cover art just the girl and the plot kind of*