Why Japan failed to build an effective convoy system

Why did Japan not adopt an effective convoy system during the Second World War?

It lacked the enormous escort fleet a convoy system required and did not shift construction priorities enough to create one.

A convoy system requires far more than ordering merchant ships to sail together; it needs a large and persistent escort force. Britain built trawlers, corvettes, frigates, destroyers, and other small ships, even slowing capital-ship programs during the Battle of the Atlantic. Italy similarly used large numbers of smaller torpedo boats for escort work. Japan lacked both the hull numbers and the willingness to make an equivalent production sacrifice, so the organizational idea could not be sustained at the necessary scale.