Japan to hk is maybe 7 hrs door to dioor, aometimes (rarely if needed, 8-9)
ive brought meat (raw), milk, seafood, veggie, cheese cake, cream cake, bread, canned drinks... back
if the meat was never froze, i just use ice gel packs and other cold stuff to pack them tgt
milk and seafood use polystyrene box (my mate buys milk in 16s- dont even ask me if he gets problem w expired milk, but doesnt seem so)
the frozen cakes are usually fine- the shop would sell thermal bags normally if i dont have one
cream cake is usually the hard one like pudding. Just tons of care. Sometimes you need to sweettalk the security people.