Vice-Admiral Nobutake Kondo
Vice-Admiral Nobutake Kondo was, after Yamamoto, the most important Japanese fleet commander in the first year of the war. He was commander of 2nd Fleet, which was the Navy's principal detached force for independent operations. His many pre-war posts (after commanding the battleship Kongo in 1932) included president of the Naval Staff College, chief-of-staff for Combined Fleet, head of the Naval Staff's operations division, and deputy chief of the Naval Staff.
Kondo was in overall command of the naval forces supporting the invasion of Malaya, Sumatra, and Java in the great opening offensive, and also overall commander for the foray into the Indian Ocean shortly thereafter. Kondo led the main "Covering Force" in the Midway operation. When operating independently of the main battle fleet, 2nd Fleet's composition varied widely depending on the mission and the ships available. For example, at Midway 2nd Fleet/Covering Force included two battleships, a light carrier, and six heavy cruisers. In the Guadalcanal fighting of November 1942, 2nd Fleet comprised the small fleet carriers Junyo and Hiyo, the battleships Kongo and Haruna, four cruisers, and 19 destroyers.
Kondo was again the senior Japanese commander in both the Battle of the Eastern Solomons and the Battle of the Santa Cruz Islands-- however, in both actions he also personally took command of a segment of the multiple dispersed groupings the Japanese customarily deployed in their invariably complex naval operations. For example, in the Santa Cruz battle he sailed with the "Advance Force" of two battleships, four cruisers (his flag was in heavy cruiser Atago), plus destroyer screen, which cooperated closely with the carrier Junyo, which howevr manoeuvred independently with its own destroyer escorts (the complicated dispositions of Japanese naval operations are usually more easily summarized than described in detail).
After the first Naval Battle of Guadalcanal in November '42, Kondo decided to personally lead the battleship Kirishima along with cruisers Atago, Nagara, Sendai, and Takao, in what was to have been a decisive attack to put Henderson out of commission through a massive nocturnal shelling. Instead, he ran into an American task force with battleships Washington and South Dakota, and was defeated, losing the Kirishima. This marked the turning point of the entire Guadalcanal campaign. In a conference held by Yamamoto aboard the battleship Yamato on November 22nd to assess the results of the recent battles around Guadalcanal, Yamamoto (according to Ugaki's diary) expressed to Kondo "his gratitude and respect for attaining the good result, overcoming many difficulties." Perhaps this was just politeness, but Kondo did subsequently serve as Deputy Commander of Combined Fleet, and in fact took over briefly as acting commander on Yamamoto's death in April '43. But he was apparently tainted by the Guadalcanal failures, and was soon removed from sea-going commands, or any positions of real authority. In fact, I have been frustrated by my inability to find virtually any reference to him at all after April 1943, except for a single mention about being appointed to the Supreme War Council in the shake-up of May 1945 (however, the Supreme War Council's main military members were the chiefs-of-staff and Ministers for the Army and Navy respectively, and Kondo definitely did not hold one of these posts at that time. Along with the Prime Minister and the Foreign Minister, these were known as the "Big Six" and directed Japanese policy in the last months of the war).
Kondo did however survive the war.