To shore up losses incurred during the Russo-Japanese War (1904-1905), the Imperial Japanese Navy (IJN) was given approval for the construction of new warships. In June 1904, the Emergency Fleet Replenishment Budget gave resources to this initiative and the cruiser Tsukuba, and her sister Ikoma, were realized from the venture. The warships were used to replace IJN Yashima and IJN Hatsuse lost to Russian naval mines in the early going.
Tsukuba was laid down on January 14th, 1905 and commissioned on January 14th, 1907 - too late to see service in the conflict with Russia. Nevertheless the two-strong group continued service into the post-war period. However, by this time, ever-more powerful battlecruisers were being completed for the IJN and this forced a reclassification of Tsukuba to that of "battlecruiser" on August 28th, 1912.
As completed, Tsukuba displaced 14,000 tons under normal load and 15,600 tons under full load. She showcased a length of 450 feet with a beam of 75 feet and a draught of 26 feet. Power was from 20 x Miyabara boilers feeding 2 x vertical triple expansion steam engines driving 20,500 horsepower to 2 x shafts. Maximum speed could reach 20.5 knots with ranges out to 5,000 nautical miles. The crew complement numbered 879. Armor protection ranged from 7" at the belt and turrets to nearly 8" at the conning tower. Decks were covered in 3" of protection.
Armament was led by 4 x 12" main guns with 12 x 6" secondary guns. 12 x 4.7" guns were also carried as were 4 x QF 3-pounder Hotchkiss weapons. A torpedo-laying element was also installed by way of 3 x 450mm launch tubes - a common feature of warships of the period.
Throughout the decade, Tsukuba undertook several peacetime voyages to America and Europe. It participated in the United States Navy's "Great White Fleet" passage through Japanese waters during October 1908. The warship remained in service by the time of World War 1 (1914-1918) and was used to blockade Tsingtao, China as it remained under German control (by treaty). She was then used to hunt the German East Asiatic Squadron which was ultimately destroyed at the Battle of the Falklands in December of 1914. From then on, Tsukuba was recalled home and remained there for the duration of the war.
On January 14th, 1917, her magazine ignited when she berthed at Yokosuka which killed between 200 and 300 of her crew. The blast was blamed on aging shell powder which combusted unexpectedly. The vessel sunk but not completely, leading her to be raised after some effort. The warship then served as a target for IJN aviators before being removed from the Naval Register on September 1st, 1917, stripped of her war-making usefulness and sold for scrapping in 1918.
Her sister, IJN Ikoma, was scrapped in 1923 under the terms of the Washington Naval Agreement of 1922.