I don’t think they had the ability to take away. One, on their best day, they never had the amphibious assault capability the United States had. It’s one thing to land 1500 Japanese Marines on Wake Island facing six 5 inch guns. It’s a whole other kettle of fish to take enormous Hawaii, with the remainder of a very pissed-off u.s. Fleet, Battleship sized Coast defense guns strategically arranged on High Ground around the island. And a fairly large US Army Force. Add in that it was beyond the range of any land-based bombers for support. Taking hawaii was never in the cards for them.
Japanese had about 5000 walking infantry that would have to wade ashore since they would have to unload 100’s of yards from the beach at the reef surrounding Midway.
http://www.historynet.com/midway-islands-undaunted-defenders-may-96-world-war-ii-feature.htm
Alerted by his code-breakers that the Japanese planned to seize Midway, Admiral Chester W. Nimitz, commander in chief, PacificCommand, flew to the atoll on May 2, 1942, to make a personal inspection.
Following his inspection, Nimitz took Simard and Shannonaside and asked them what they needed to defend Midway. They told him their requirements.
“If I get you all these things, can you hold Midway against a major amphibious assault?” Nimitz asked the two officers.”
Yes, sir!” Shannon replied.
It was good enough for Nimitz, who returned to Oahu. On May 20,Shannon and Simard received a letter from Admiral Nimitz, praising their fine work and promoting them to captain and full colonel, respectively.
Then Nimitz informed them that the Japanese were planning to attack Midway on May 28; he outlined the Japanese strategy and promised all possible aid.
All the while the Marines continued digging gun emplacements, laying sandbags and preparing shelters on both islands.
Barbed wire sprouted along Midway’s coral beaches. Shannon believed that it would stop the Japanese as it had stopped the Germans in World War I.
He ordered so much strung that one Marine exclaimed: “Barbed wire, barbed wire! Cripes, the old man thinks we can stop planes with barbed wire!”
The defenders also had a large supply of blasting gelatin, which was used to make anti-boat mines and booby traps.
On May 25, while the work continued, Shannon and Simard got some good news. The Japanese attack would come between June 3 and 5,giving them another week to prepare.
That same day, the light cruiser St. Louis arrived, to deliver an eight-gun, 37mm anti-aircraft battery from the Marine 3rd Defense Battalion and two rifle companies from the 2nd Raider Battalion.
On May 26, the ferry USS Kittyhawk arrived with 12 3-inch guns,5 M-3 Stuart light tanks.
By June 1, both Sand and Eastern islands were ringed with coastal defenses. Six 5-inch guns, 22 3-inch guns and four old Navy 7-inchguns were placed along the coasts of both islands for use as anti-aircraft and anti-boat guns.
As many as 1,500 mines and booby traps were laid underwater and along the beaches.
Ammunition dumps were placed all around the islands, along with caches of food for pockets of resistance and an emergency supply of 250 55-gallon gasoline drums.
Midway had practically everything it needed for its defense. Along with the 121 aircraft crowding Eastern Island’s runways,Midway had 11 PT-boats in the lagoon to assist the ground forces with anti-aircraft fire.
A yacht and four converted tuna boats stood by for rescue operations, and 19 submarines guarded Midway’s approaches.
You forgot to mention:
The Hawaiian Operation was not the primary focus of the war, the goal of the war was to take the Southern Resource Area.
Japan did not have the troops available to take Oahu, the Army only allocated about 10 or 11 Divisions worth of troops for the entire Pacific war, the rest were needed in China.
Japan did not have the shipping to carry troops and supplies to invade Hawaii. Indeed Japan started the war with a shortage of shipping.
Japan had no fleet train to keep the IJN in Hawaiian waters for more than a few days.
Invading Hawaii was impossible for Japan, because they did not have the resources and foolish because it would have lost them the war.