The Basketball Saruhiko Played [Kuroko no Basket Fanfic]

A girl from the mountains was brought by Riko in the city, exploring the life living inside a place full of discord and boisterous noises, different from her secluded, peaceful life. She then discovers that Riko is a coach from a certain club, Seirin Highschool Basketball Team. She then tells her that she doesn't know what basketball is about.

What is the truth behind the mysterious girl suddenly entering the lives of Riko's team? What would be her purpose? Who is Saruhiko Reimei?