I'm gonna be going to Shanghai for around 4 days, then taking a cruise from Wusongkou to Japan

I'm gonna be going to Shanghai for around 4 days, then taking a cruise from Wusongkou to Japan and back for another 6 days. I know this is more than the 144 hours twov, but does the short trips to Japan count as splitting the days apart, or do I have to do any special procedures to extend the entire trip?