I'm doing basically this exact trip in reverse (i live in hong kong) solo starting on saturday.
Moving up the east coast of china, then ferry to south korea, ferry to japan, ferry to russia the whole trans-siberian from vladivostok to mosow i.e. the real 'trans-siberian' not the trans-mongolian or the trans-manchurian, stopping off a few times along the way of course as i dont want to sit in a train for 7 days as i pass some of the most amazing things on earth outside. as the above poster said trains in china re cheap and efficient and come highly recommended!
I'm figuring about 12 weeks for this trip but i could easily double that and still have plenty to see if i had the time to extend it!
Any questions about logistics of it or my route in more detail please ask!
Oh yeah and i've picked the big cities because I've already done most of scenic china i.e. yunnan, guilin etc, so i figure its time to catch these cities
as for the point about taking the ferry to japan, sure you COULD fly but wouldnt it be so much cooler if you went all the way from the uk to japan without flying? like a REAL overland journey?
Thats my intention anyway!