DHL Express handed unaccompanied baggage to Sagawa Express

I had a desktop PC and some clothes shipped to me in a flight case by DHL from the UK to Japan as I didn't want to risk checking it in on my flight via China and having it held up there for any reason. It reached Japan three days later, cleared Tokyo customs, then DHL handed it to a third party which I learn is Sagawa Express. The box weighs 23kg.

For DHL it was supposed to arrive end of Monday but it is now over 48 hours and I'm getting worried. The tracking says it is held at a Sagawa branch. Does anyone have any advice on how long this might take and what to do if it goes quiet – thanks.