Prince of Tennis: My Sister at Hyotei

When I listen to sleep books, the more I listen to it, the less I can stand it. First of all, the heroine is in high school and is in the same class as Atobe and Ninzu. So, as a good baby, Feng doesn't even call her senior? Call a classmate? Secondly, as a high school student, going to be the tennis manager of the middle school? Also, as a Japanese samurai, Nanjiro has publicly displayed his dual-sword style, so how could he not know about it as his daughter?