Construction of the Tsukuba-class cruisers was ordered under the June 1904 Emergency Fleet Replenishment Budget of the Russo-Japanese War, spurred on by the unexpected loss of the battleships and to naval mines in the early stages of the war. These were the first major capital ships to be designed and constructed entirely by Japan in a Japanese shipyard, albeit with imported weaponry and numerous components. However, Tsukuba was designed and completed in a very short time, and suffered from numerous technical and design problems, including strength of its hull, stability and mechanical failures. The ship was reclassified as a battlecruiser in 1912.
Tsukuba was laid down on 14 January 1905, launched 26 December 1905 and commissioned on 14 January 1907 at Kure Naval Arsenal, with Captain Takenouchi Heitaro as her chief equipping officer and first captain. Shortly after commissioning, and with Admiral Ijuin Gorō on board, Tsukuba was sent on a voyage to the United States to attend the Jamestown Exposition of 1907, the tricentennial celebrations marking the founding of the Jamestown Colony. She then traveled on to Portsmouth, England and returned to Japan via the Indian Ocean, thus circumnavigating the globe. After her return to Japan, Tsukuba was assigned to Captain Hirose Katsuhiko and escorted the United States Navy’s Great White Fleet through Japanese waters on its around-the-world voyage in October 1908. Captain Isamu Takeshita was captain of Tsukuba from July through September 1912, followed by Captain Kantarō Suzuki to May 1913, and Captain Kanji Kato from December 1913 to May 1914. Tsukuba served in World War I, initially during the blockade of the German port of Tsingtao in China during the Battle of Tsingtao from September 1914 as part of Japan's contribution to the Allied war effort under the Anglo-Japanese Alliance. After the fall of the city, Tsukuba was sent out as part of the search for the German East Asiatic Squadron in the South Pacific until the destruction of the German squadron in the Battle of the Falklands in December 1914. Tsukuba remained in Japanese home waters in 1915 and 1916. On 4 December 1915, Tsukuba was in a fleet review off of Yokohama, attended by Emperor Taishō in which 124 ships participated. A similar fleet review was held again off Yokohama on 25 October 1916. On 14 January 1917, Tsukuba exploded while in port at Yokosuka. Some 200 crewmen were killed immediately, and over 100 more were drowned as the cruiser sank in shallow waters within twenty minutes, with a total loss of 305 men. The force of the explosion broke windows in Kamakura, more than twelve kilometers away. At the time of the disaster, more than 400 crewmen were on shore leave, which is why so many survived. The cause of the explosion was later attributed to a fire in her ammunition magazine, possibility through spontaneous combustion from deterioration of the Shimose powder in her shells. The masts, bridge and smokestacks of the vessel remained above water, and afterwards, her hulk was raised, and used as a target for naval aviation training. It was formally removed from the navy list on 1 September 1917 and broken up for scrap in 1918.
