Tamon was born on August 17, 1892 at Koishikawa, Tokyo. He was the third son of Yamaguchi Muneyoshi, an old samurai that served the Matsue Domain. He was nicknamed 'Tamonmaru' when he was a kid.
He graduated from Junior High on 1909, he was a very bright student ever since. He ranked 21 out of 150 people during the enrollment at the Imperial Japanese Naval Academy on September of 1909, together with Onishi Takijiro, which eventually will sprang a rivalry between them. Aside of his outstanding grades, he's also great in Kendo and considered one of the best of their class. Yamaguchi graduated from the 40th class of the Imperial Japanese Naval Academy in 1912, ranked second out of 144 cadets.
On July 17, 1912, he served as a midshipman on protected cruiser Soya. On May 1, 1913, he was transferred to the dreadnaught battleship Settsu until he was promoted as an ensign on December 1, 1913. On May 27, 1914, he served on the protected cruiser Chikuma (1911). During the outbreak of World War 1 on July 28 1914, he transferred to the semi-dreadnaught battleship Aki on February 1, 1915. On December 13, 1915, he was promoted to a sub-lieutenant, he attended naval gunnery base education and torpedo base education on June 1, 1916. On December 1, 1916, he becomes a member of the 3rd Submarine Fleet. He assisted the 2nd Special Task Fleet on May 1, 1918 and served on Destroyer Kashi on July 5, 1918.
During the conclusion of World War 1 on November 11, 1918, he was promoted as a lieutenant on December 1, 1918, and he was assigned to a navigation unit with the naval squadron escorting submarines from the Kaiserliche Marine as part of the reparation payment from the Germans at the end of World War 1. On February 1, 1919, he was assigned as a crew on Yokosuka and becomes a part of Yokosuka Defense Corps on July 24, 1919. On October 19, 1919, he was transferred to Kure and on December 1, 1919, he attended advance torpedo base education and was transferred to Sasebo as part of the Sasebo Defense Corps, one year after. He becomes a representative of Japan to the United States and becomes a resident on February 25, 1921, he attended in Princeton Academy until he was ordered by the Empire of Japan to return on March 10, 1923. Upon on his return on May, he was assigned as to serve on the battleship Nagato on June 15, 1923, for six months. On December 1, 1923, he becomes an instructor on submarine base education, he attended the Naval Staff College a year after and was promoted to Lieutenant Commander, he graduated on November 25, 1926 and assigned as a member of the SubRon 1. He becomes a member of the Imperial Japanese Navy General Staff on November 15, 1927.
He was promoted to commander on December 10, 1928. He becomes a Japanese delegate during the London Naval Conference on November 12, 1929, the London Naval Treaty was signed on April 22, 1930, Yamaguchi strongly opposed the terms of the treaty together with Yamamoto Isoroku. On July 1, 1930, he was assigned as an executive officer of the light cruiser Yura, he becomes a member of the IJN 1st Fleet on November 15, 1930. On September 20, 1932, Toshiko, Yamaguchi's first wife, died after giving birth for their third son. He was then married to Takako, niece of Vice Admiral Shikama Kosuke, who was introduced by Yamamoto. On November 15, 1932, he becomes an instructor in Naval Staff College and on December 1, 1932, he was promoted to a captain. He traveled again to America on June 1, 1934, and becomes a naval attaché to the United States. He was ordered to return on November 18, 1936.
He takes command on the light cruiser Isuzu on December 1, 1936, seven months before the outbreak of the Second Sino-Japanese War on July 7, 1937. He takes command on the battleship on December 12, 1937. He was promoted to a Rear Admiral on November 15, 1938. He commanded the First Combined Air Group which participated on the bombing of Chongqing from February 18, 1938 to August 23, 1943 along with Onishi with over a hundred thousand of civilian casualties while the Japanese lost of dozen of bombers during the run. On December 15, 1938, he commanded the IJN 5th Fleet. He was appointed as the commander of the 2nd CarDiv on November 1, 1940, which composed of carriers, Souryuu and Hiryuu, and destroyers from DesDiv 23, he issued commands from then carrier Hiryuu.
On December 7, 1941, 2nd CarDiv which is part of the Kido Butai participated on the attack of Pearl Harbor and caused damaged with 4 battleships sunk, 4 battleships damaged, 1 battleship grounded, 2 auxiliary ships sunk, 3 cruisers damaged, 3 destroyers damaged, and 3 auxiliary ships damaged with 188 aircraft destroyed and 158 more were damaged, 2,403 killed and 1,178 wounded, the IJN lost 29 aircraft and 4 midget submarines. He participated in the Battle of Wake Island which the 2nd CarDiv saved Admiral Goto Eiji's force from destruction. The 2nd CarDiv subsequently participated on the raids in the Indian Ocean which sunk 1 carrier, 2 cruisers, 2 destroyers, 1 armed merchant cruiser, 1 corvette. 1 sloop and 23 merchant ships with more than 40 aircraft destroyed.
On June 4, 1942 was the Battle of Midway. He argued with Admiral Nagumo upon a reconnaissance plane discovering an American aircraft carrier within Midway Atoll, Nagumo wants to switch bombs with torpedoes while Yamaguchi wants to carry the assault as soon as possible. At 10:25 while making launch preparations, Souryuu was attacked by 13 dive bombers, three bombs directly hit the carrier, Souryu goes dead on water and was scuttled afterwards. After the USN destroyed three of the four IJN carriers, Yamaguchi immediately issued an attack on USS Yorktown CV-5, two attacks were made and crippled the carrier. At 17:03, Hiryuu was attacked by another 13 dive bombers from USS Enterprise CV-6 while launching another attack on Yorktown, Hiryuu received four bombs from the aircraft, and goes dead on water afterwards.
Yamaguchi gathered 800 of his crew, they yelled banzai three times, played the national anthem until he gives his farewell speech and ordered the ship to be abandoned. Yamaguchi alongside with Hiryuu's captain, Captain Kaku Tomoe, stayed and decided to go down with the ship. The two shared naval biscuits and water while calmly admiring the moon. 418 crew also decided to stay, after the evacuation, Makigumo failed to scuttle Hiryuu and was left abandoned. Hiryuu upended and sank by the bow afterwards.
Yamaguchi died on June 4, 1942 within Pacific Ocean near Midway Atoll, he was posthumously promoted as a Vice Admiral on June 5, 1942. He decorated with the Order of the Raising Sun 4th Class, Order of the Sacred Treasure 2nd Class, and Order of the Golden Kite 1st Class.