I am not aware of whether the Hang Seng and Nikkei 225 in particular work the same as other index futures but believe they do in so far as they trade above or below fair value to their indexes and then converge upon expiration.
You might be able to find more info by checking their respective exchange websites:
http://www.hkex.com.hk/index.htm
http://www.ose.or.jp/e/index.html