香港>上海>大阪轉機問題

只要持有回鄉卡，就可以在等候在轉機期間，離開機場乘地鐵去市中心逛逛，浦東機場和虹橋機都有地鐵，十分方便。

Check the condition of carriage / sub-class of ticket. You can always enter Shanghai, but the condition may not allow and this needs to be solved with money.

Also check out about any airport tax applicable.