What if the Axis had actually considered their actions in 1941 logically?
1941: Instead of attacking the Soviet Union and starting a two-front war (which he also wanted to avoid in OTL), Hitler decides to focus all German war efforts on Britain. On December 7, Japanese planes bomb the ships at Pearl Harbor, but they also bomb the repair depots, fuel storage, and other facilities. A few days later, the US carrier fleet is also targeted out on the open ocean, truly crippling the US Navy and enabling Japan to eventually take control of most of the Pacific Ocean virtually unopposed. Emperor Hirohito then somehow assures Hitler that Japan can single handedly defeat the US, persuading Hitler to not declare war on the US. Meanwhile, whatever remains of the US Navy is slowly but steadily rebuilt along the West Coast.
1942: Without American military assistance against Germany, British imports suffer horribly in the Battle of the Atlantic, thus enabling Operation Sealion to be remotely feasible. As time goes on, the feasibility of Operation Sealion increases, paving the way for the final battle between the Kriegsmarine and the Royal Navy. Meanwhile, British forces in Africa suffer major defeats, especially after Spain joins the war by attacking Portugal and providing much-needed support for Italian forces in Africa. Egypt is mostly overrun, but the job isn't finished yet. Also, Japanese forces land in Hawaii, mostly securing Japanese control of the Pacific and enabling Japanese attacks on the American West Coast, especially California, where the US Navy is desperately trying to rebuild.
1943: Finally, after being postponed indefinitely and even cancelled, Operation Sealion begins. With the RAF and British air defenses destroyed, the Luftwaffe and Kriegsmarine go all-out on the Royal Navy, pounding it straight into the ocean while the Japanese launch a big attack in Asia a few weeks prior to distract British forces. The massive Japanese attack secures Japanese control of New Guinea, while Italian forces with German and Spanish support (especially Rommel's infamous Afrika Korps) chase the British all the way down Africa. The Wehrmacht soon secures beachheads in southern England during November and December.
1944: After securing numerous beachheads in southern England, the Wehrmacht destroys the British army with blitzkrieg tactics, which can now be used again as they are once again fighting on land. They then speed toward London, blocking any and all potential escape routes, whether land, air, or sea. The British government is then forced to sign a peace treaty, allowing Hitler to keep all his gains in Scandinavia and Western Europe, although Allied governments-in-exile are allowed to remain in British custody. Meanwhile, Italy is allowed to take most British and French colonies in Africa, but Spain gains a few small colonies as a 'thank you' for joining the war, as well as Portugal and all her colonies. In Asia, Japan is allowed to keep all her Asian conquests so far and reorganise the land however they want to, but Britain is allowed to keep Canada, Australia, New Zealand, and India. After this, the Axis is finally free to attack the United States from both sides. Also, Northern Ireland is given a referendum on whether to join Ireland or remain in the UK. They vote to remain, but Anglo-Irish tensions continue nonetheless. Finally, Japanese troops previously stationed in the Aleutian Islands begin advancing into the rest of Alaska. Hitler then considers starting Operation Barbarossa, but his generals persuade him not to.
1945: After preparing supply routes and revising strategies and tactics, the Third Reich declares war on the US. This comes right after President Roosevelt's death, which has proved to be demoralizing against the near-constant Japanese bombardments on the West Coast. He is succeeded by Harry S. Truman. Now that Britain has sued for peace, America will have to fight a two-front war against two military giants. However, fortunately for the US, the American people are willing to produce military equipment 24/7 while Hitler allows the German people to only work 9-to-5, although some decide to work extra hard for their Führer. Also, the Manhattan Project is then successfully tested in August.
1946: The American defense proves effective in repelling Axis attacks, and soon the US Navy returns to action, successfully defeating the Japanese Navy in a few battles. The Kriegsmarine is also repelled by coastal fortifications while the mighty Wehrmacht is repelled by the fledgling US Army.
1947: In the years since Pearl Harbor, the US has managed to rebuild a few aircraft carriers and they are now recommissioned with all-new crews, pilots, and aircraft. Many atomic bombs have also been built since the first ever successful testing of the atomic bomb in 1945, and the new aircraft carriers are now equipped with them. Armed with this new atomic arsenal, the US Navy sets out to obliterate the Japanese.