Why the bombers attacking Force Z lacked fighter escort

Would Japan escort the bombers attacking a carrier-equipped Force Z?

Not in this operation: the forward bases had only just received the bombers, and no fighters with suitable range were available there to escort them.

Japan possessed long-range fighters, but the relevant forward airfields had become operational only a day or two before the strike and received the bombers just in time for the mission. Fighters with the required range were not present at those fields. A carrier combat air patrol would therefore meet unescorted bombers. That creates a much more favourable interception problem than a simple comparison of Japanese aircraft inventories suggests.