I want to stay in China for a year and join my brother.

My brother is in China but he has a diplomat visa and will be staying in China for two years. I'm not sure which type to get because he doesn't have an working Z type or student X type. I would like to stay in China for a year even if that means having a 90 day duration stay and going back and forth from HK to China every 3 months to reset it.