UK-Shanghai (change airlines)-Osaka

Jon, the main detail here is that your itinerary is eligible for 24 hour visa free transit and you do not need any kind of visa. Also, you do not have to do anything in advance. At the time of your check-in in London you will just declare that you are traveling to Japan under 24 hour visa free transit scheme.

Now, I do not have all the information to be able to answer the rest of your questions because I do not know whether you are traveling under a single ticket or two separate tickets. Both are fine in any case. In case if you travel under a single ticket (single booking), you will just walk from one gate to the other and you do not need to perform any formality nor to fill out any forms. Also, you will not be a subject to immigration or customs inspections. Your luggage will be transferred automatically by airport staff. You will just encounter a security check between the two gates (metal detector and similar stuff). In case of two separate tickets the procedure is different, but even here you do not need any kind of visa. If something has remained unclear, you can ask a follow-up question right here. I wish you a nice journey.

Thanks for the reply. I am travelling under two separate tickets and the information you’ve provided is very clear.

Jon, your itinerary is eligible for 24 hour visa free transit with two separate tickets,of course. Here are the procedures you will perform in the exact sequence:
- You are advised to have your flight tickets as printouts or at least as good screenshots
- Upon landing in Shanghai you will fill out arrival card and tick transit in the appropriate box
- Perform fingerprinting at automatic fingerprinting machine
- Approach 24/240 hour visa free transit where you will present your flight tickets, yozr arrival card and fingerprinting receipt
- You will receive a temporary entry permit in your passport
- You will cross the immigration
- You will collect your luggage
- Head to the check-in and drop off your lugagge
- Head to the gate for your flight to Osaka

This is all inevitable since you travel on two separate tickets, but you should not worry because 3 hours are enough. In any case, just be agile and just follow the instructions presented here. Have a nice journey.