Short answers, pulled from the story.
The Imperial Japanese Navy was formally established in July 1869, two months after the last combat of the Boshin War. A centrally controlled national navy was not fully realized until 1871, when the domains donated their forces to the Meiji government.
By 1920 the Imperial Japanese Navy was the third largest navy in the world, behind the Royal Navy and the United States Navy. Under the 1922 Washington Naval Treaty, Japan was allotted 315,000 tons of capital ships compared to 525,000 tons each for the United States and Britain.
The Battle of Tsushima in 1905 was the decisive naval engagement of the Russo-Japanese War, in which Admiral Togo led the Japanese Grand Fleet to an overwhelming victory. Out of 38 Russian ships, 21 were sunk, seven captured, and six disarmed, while Japan lost only 116 men and three torpedo boats. The victory established Japan as a recognized major naval power.
Japan entered World War I on the side of the Entente under the 1902 Anglo-Japanese Alliance. Japanese forces achieved the world's first successful sea-launched air strikes at the Siege of Tsingtao in September 1914. Japan also sent destroyers to the Mediterranean, escorting 788 Entente transports from a base at Malta, and seized German possessions in northern Micronesia.
Kantai Kessen, meaning decisive battle, was the IJN's core strategic doctrine. It assumed the U.S. Navy would cross the Pacific, be degraded by Japanese submarines en route, and then be destroyed in a single large fleet engagement in waters close to Japan. The doctrine derived from the writings of geopolitical theorist Alfred T. Mahan and shaped Japan's warship design and construction priorities throughout the interwar period.
The IJN was defeated through a combination of strategic miscalculation and industrial disparity. Japan under-invested in antisubmarine warfare and convoy protection, leaving its import-dependent economy vulnerable. Between 1942 and 1945 the United States produced 3,200,000 tons of warships against Japan's 550,000. Catastrophic aircrew losses at Midway and the Battle of the Philippine Sea left Japan without a functioning carrier air arm by late 1944.