I've spent way too many hours reading these last night and decided to give my own a try. Oddly, I haven't found an AAR with the unmitigated Japanese success we've experienced. I am not going to try complete details, especially as its already a month into the war and I don't know them exactly.
I'm playing with a real life friend of mine who got me into WitP. Our first PBEM game had me playing the Allies. In March of '42 I resigned after losing most of my cruisers, 3 US carriers and having sunk ... about 2 CAs. Clark Field still stood, but Manilla had just fallen and Singapore was long gone. I also had a chunk of troops trapped in Rangoon and dying rapidly (two weeks to live, maybe). I firmly believed there was no possible way to prevent him from conquering India. So we started over and switched sides.
As the Allies, I had disgustingly concluded the only possible plan was to run away with everything. He professed that led to inevitable defeat, so I knew I would face resistance playing as Japan.
STRATEGY
That might be good. I don't have one.
The historic plan seems reasonable to me, especially with historic first turn. My only strategic assertions at the beginning (that I would proceed to violate) were to crush Singapore quickly, grab the Oil and ignore the US after pasting Pearl.
The 56th Division from Osaka and the 38th Division from Hong Kong (after taking it) were therefore allocated to Singapore on paper.
The Shinano was canceled.
INITIAL TACTICS
Here I actually came up with something, although two of the three failed.
I wanted to advance weakly in Malaya, sending very little reinforcements to the north. From conversations, I knew the Allies would attempt to delay the advance, buying time in northern Malaya. I figured I'd let him. Then land 2+ divisions and some tanks at Mersing, take Johoru Baru and cut off the northern troops from Singapore.
In the Phillipines, I wanted to hit Lingayen and therefore cut off the divisions outside of Clark, then base airplanes at San Marcelino. Also hit Naga (and north of Naga) to wipe out those divisions.
In China, from reading advice, the plan was to concentrate firepower and crush Changsa. I also went for an end run around the northern side into Lucknow.
INITIAL BATTLES
The KB bombed Pearl Harbor for three days, sinking only the Oklahoma. Lots of ships got pounded and my airplane loses were not too bad, but only the one BB sank.
Wake island fell on the first day.
Invasions at Aparri and Vigan in the Phillipines continued as normal (not entirely in line with the strategic plan already!) with everything going as expected. The silly NLF in the south got crushed, but pulled off the beaches by its transports and returned to Palau. The Japanese naval aviation and navy blasted various transports in the islands, most spectacularly when the destroyers from Hong Kong were caught by a cruiser group near Jolo and blown out of the water.
The invasion at Khota Baru eventually managed to take it. As per plan, the troops landing in the north did very little initially. As walking through that one hex of jungle is hell, the 55th division (headed for Burma) would be moved to Bangkok via transport.
SECOND WEEK (roughly)
Returning to port, I for some reason set two KB Zero squadrons on 100% CAP and forgot about them. By the time they made it to Truk, morale was about 30 and exhaustion up. Even once the KB had refitted its squadrons, those two carriers were left behind to heal their morale and act as a reserve.
The Phillipines proved a total pain in the rear. I could not transport troops in at nearly the speed I desired, making my tactical concept utterly meaningless. I had troops piling up at Vigan because I was afraid to land engineers at San Marcelino without the big troops and I couldn't get the divisions imported fast enough. I cannot even begin to explain, but I basically lost all track of what I was doing other than piling up units. None of this was caused by the allies, it was all self inflicted confusion.
Bombing of Singapore was hurting it and army airplanes began to be based on Khota Baru to aid in the bombing. The AVG showed up in Singapore and shredded a bunch of Oscars. The long range Zeroes (escorting Nells from Saigon) would show up sometimes to beat them down, but my de-facto plan for killing the AVG was mainly to blow them up on the ground using the level bombers. I did not want to 'waste' my elite navy pilots against more difficult fighters. The 33rd and 55th Divisions sitting in Bangkok and papered in for Burma began their (silly) quest for perfect condition (full TOE, no disabled squads).
Hong Kong fell and the 38th Division began refitting. The harbor was cleared in two days thanks to a pre-positioned TF of many many minesweepers. My forces were quietly massing for Changsa at Nanning and Wuhan. Another major group moved one hex west of the rail junction towards Homan, hoping to hold defensively there. Recon planes seemed to confirm the movement of the NE Chinese troops to Yunan, opening the road for the northern end run.

