spoiler :D
They play for different teams except for the time they represent Japan. Both are in the Japanese national volleyball team, so they still have to practice and play together.
Hinata and Kageyama have had a special bond from the start. Now they respect each other as rivals and are unstoppable as teammates. Even Kageyama (and I'm pretty sure he was waiting for Hinata to finally return to Japan) admitts that Hinata could be better than him now. From the beginning they got the best out of each other.
(What I like about Karasuno, even after so many years, the volleyball team is still around and going to games together to support their former teammates and so on.) <3

Okay but I just wanna know if Hinata and Kageyama stay friends or if they really go extreme and don't ever talk to each other again;-;