EMS Japan to UK

Don't know why parcels sent from Osaka international always take longer than Tokyo international, my parcel has been in the air for 5 days already with no update since "dispatched to UK". I have had many parcels shipped from Osaka but never had one stuck on air for 5 days... Has anyone had similar experiences before ? Feeling kind of concerned since it is quite valuable :(

I cannot comment on any comparison between Osaka and Tokyo, but I can tell that some parcels on their way from Japan are taking some time to get on an aircraft (probably due to reduced flights between Japan and some other countries - Japan Post does not have their own aircraft, as against UPS or Fedex for example). Another thing I've noticed is that sometimes upon arrival in the UK, scanning is not done at every stage, so that there might be delay with the tracking updates. Best wishes.

The parcel has left Osaka.

So it is probably sitting at border force not scanned as arrived.

Plus it is Xmas, so times are extended as more parcels are flying around.

If you've recently sent a parcel, just a few things to keep in mind: It's right near Christmas/New years, so obviously there will be way more mail than usual.

Secondly, borders in Japan are closed (yet again, ahhhh) so it's slowing down flights as well. And lastly, keep in mind that the whole world has been disrupted as of a couple of years ago. Industries are changing, people are changing and the Military around the world is also cleaning up corruption from all countries, so it takes time for things to happen.

For most of the last two years postal services worldwide have been disrupted and air cargo space is at a premium. Since the start of the covid pandemic I have sent and received several parcels from Japan and had several delivered to Japan. In most cases, full priority airmail that would usually take three to five days has been closer to 14 days and tracking information has shown often items sit for a week at a location waiting for space on a plane - that is the bottleneck. There is a very good/comprehensive Japan Post web page listing the restrictions and what forms of postage are available (if any).
As an example, currently I am waiting on a small item from California. Ordered 12th dec - order fulfilled 18th December (yes, there was a weekend and Christmas rush affecting that). In the last twelve days the item has moved a couple of hundred km to an airport in California (last update was four days ago). Eventually it will get on a plane and once in Japan I know the transit times across Tokyo mean I will get it promptly, but only once it has done the cross Pacific leg. The 10-business days delivery indicated is long gone, but in this case it is only a US$40 item so I am not too worried.
You just need to be patient.

This has become an old thread now (and I wonder if the OPs parcel made it to its destination), but I do have a couple of additional comments that might be useful for other people.
First, the tracking site may include more or less information depending on the service. If I use the one normal service site I get quite limited information stating simply "in transit". I was recommended to use another service and that provides many more lines of information (currently 28 lines), including that my parcel was accepted "international dispatch ready" twice on the 1st and 11th of Jan. Yesterday it appears to have finally made it onto a plane and today might actually be in Japan. i.e. the parcel spent four weeks in California before actually making much progress (with luck I'll have my Christmas present in two more days as Japan delivery is pretty efficient).
Second point is that sending/receiving parcels internationally has been slow for some time and likely to remain slow/disrupted for quite a while longer yet. While this is a sample of one, my other shipments over the past twelve months have all also been delayed, but not to the same extent.

Which tracking service are you using to provide extra information into the details of the parcel? I am using both Japan Post and EMS and there are only 4 lines, the most recent has been stuck at Jan 12, 2022 12:20 PM Departed from export office Tokyo.

I was recommended to use https://ppxtrack.epgshipping.com/
I had never heard of this one before a few weeks ago. While the package was sent via USPS, their system took a while to update with detailed information.
If I plug my tracking number into Japan Post this morning I only get four lines of information - it (my parcel) made it to Kanagawa yesterday.