At the time of the Ceylon raid the IJN indeed had dozens of divisions with little to do in Malaya-Singapore, HK, Burma, Thailand, the PI (with US forces limited to Corregidor) and the DEI The Midway operation had 3 large fleets converging on Midway and large distraction fleets in the Coral Sea and Alaska. Midway, Port Morsby and Alaska are much farther from Japan or the DEI (the source of oil) and the Marshalls. Midway had zero economic value and was intended only to lure USN carriers for destruction. Invading Midway would have been a nightmmare owing to the impossibility of deploying airborne troops and having a very small, heavily mined landing area. Attacking Midway is costly and unproductive and supplying and defending it close to Hawaii would have been very difficult. The whole Coral Sea-Midway-Alaska operation was an enormous waste of fuel (the invaluable, limited fuel in Japan, not the abundant fuel in B. Borneo and the DEI), warships, planes, troops, etc, for no gains at all. Invading Ceylon from Malaya.Burma, the DEI and Thailand with a small fraction of the fleet used by Yamamoto (mostly the fleet already used for the useless Ceylon & IO raid) and with oil from B. Borneo is a piece of cake and a much better investment, considering the reosurces gained and the isolation of India and China. As I wrote if Yamamoto uses the carriers he wasted on Darwin to invade weak Port Moresby and New Caledonia in Feb, 1942, there is no Coral Sea or Milne Bay. If after invading Ceylon, Yamamoto forgets about Alaska and consolidates the Kidobutai [6 fleet carriers, 2 CVL (Ryujo, etc,) and 2 CVE (Shoho, etc,)] and the large surface force to attack Midway, sending 4 fast battleships, 10 cruisers and 20 destroyers to shell Midway at night (destroying most of the US planes, without risking his carrier planes) and using his carrier planes to shoot down the surviving US planes which attack the bombardment force during the day and using the bombardment force planes to look for USN carriers in the area, the iJN destroys all the planes in Midway and sinks all 3 USN carriers and their escorts.