Can you please confirm what visa i would need for my cruise ?

Hi there, having difficulty trying to work out what i would need for my holiday in march. i arrive in Hong Kong on 16th march, staying 2 nights (1 in hotel, 1 on boat) then set sail for Xinjang for two nights. then on to japan. can someone please help as im unsure what entry permit i would need? ive been told we dont need one for HK and have also heard of an entry permit exemption policy if you are in china for a short time? if someone could guide me id be really grateful.

Thankyou very much, natalie