Yes, the protagonist of this article is Shinnosuke's lovely sister!
I think being Xiaoxin's younger sister should be a very happy thing! Moreover, there are very few such fanfics, so the author had to do it himself...
The heroine is not a time traveler, she is a local girl. The story is relatively long and will develop slowly. The early stage focuses on describing Xiao Kui's life. The end point in the later stage involves the Prince of Tennis and the Black Basket. The male protagonist is currently decided to be Atobe.
I hope everyone can bear with me?