The first of the two Goryo-class Ships had just been laid down when talks started within Koko no Kaigun's Naval staff about a successor ship. HMS Dreadnought had made those two ships -Goryo, and the planned Aratama- obsolete even before any work started on them. during the course of the year 1908 many designs were looked upon, from a Dreadnought Satsuma (a concept not much different from the Kawachi class ordered for construction by the IJN) to a foreign order to Britain for a straight copy of Dreadnought herself. By early 1909 attention shifted to lighter designs, with the Naval staff seriously considering a 16.800T standard unit. This plan, heavily resembling the Goryo class in overall appearance, called for a ship some 163m long, armed with six 305mm 50-caliber guns in three turrets, augmented by twelve 152mm 45-caliber ones in casemates, four more 152mm 40-caliber on deck mounts, six 76mm guns to deal with torpedo boats and three torpedo tubes. Supposed of beign capable of 23 knots, the ship would have featured a fenomenal 305mm belt armor, but also had a terrible 2.700miles endurance at 14 knots, which would have probably dictated a reduction of the armor scheme or speed in order to achieve higher values.
The Design, already funded and on the brink of beign approved, was ultimately shelved for it's whimpy armament for a Battleships and the lack of range, but also because the Naval staff was shifting its interest to a new type of Dreadnought ship that had just made it's appearance: the Battlecruiser. Impressed by the Invincible class specifications, Koko no Kaigun higher-ups started to demand speed instead of Armour for Kokoan first true dreadnought. A new design was thus prepared: displacing 17.800T the new ship featured similar armament to the Invincibles, with eight 305mm 50 caliber guns in four turrets, but arranged them on centerline to allow for a full broadside and avoid blast damage issues that prevented the Invincibles to effectively fire all of their guns in a battle line. Twelve 152mm guns of the newer 50 caliber and sixteen 76mm would have made up the secondary and anti-torpedo boat armament. Belt Armor was planned at 152mm, with 64mm decks and a maximum of 178mm turret armor. Top speed was intended around 26,5 knots and endurance at 6.000 nautical miles at 14knots.
The design was further modifed during the course of the year to address informations regarding the newer Indefatigable and Moltke class ships under construction in Britain and Germany.
When ultimately ordered, in late 1909, the two planned ships had thus further grown to fulfil the requests from the Naval staff, which called for more armor and even more speed:
They would have measured 195,2m at the waterline, for an overall lenght of 198,1m -just two meters shorter than what Kokoan shipyards allowed at the time. The planned beam was 24,4m and Draft 8,5, for a displacement of 20.329T standard and 24.608T at full load. Main armament was made of four twin turrets, housing 305mm 50-caliber Type41 guns, with the magazines carrying 100 rounds per gun. The turrets were all fitted on centerline, one on the forecastle, one at midships and two on quarterdeck, superfiring, in a design akin to the German Moltke. Secondary armament was increased to fourteen 152mm/50 guns in casemates, while the anti-torpedo boat one was reduced to six 76mm mounts, fitted in pairs on top of three of the four main gun turrets. Finally, two 450mm underwater torpedo tubes, one on each beam, completed the armament. Belt Armor was 203mm thick, with an upper strake which thickness ranged from 102 to 152mm. The belt tapered down to 64mm outside the citadel, almost reaching the bow and stern. Main deck was 64mm thick, with a 32mm protection on the forecastle and 38mm on the quarterdeck. Below the Waterline the Magazines were protected by 64mm anti-torpedo bulkheads. Main gun turrets were protected by 229mm plates on face and 83mm ones on the roof. Barbette armor was 229mm thick. The forward conning tower was protected by 254mm of armour, the aft one by 102mm plates. Engine-wise, the projected units clearly showed the high-tier ambition of the Naval Staff: thirty-eight Yarrow boilers, split between six compartments and fueled by coal -sprayed with oil for better combustion- powered four Parsons team tubines, planned to generate as high as 82.539shp. This monstrous power drove four three-bladed propellers and was intended to push the ships close to the 28,5-knot mark. Endurance was planned at 6.830 nautical miles at 14 knots. Complement was planned at 924 officers and men.
Named Aomegami (Turquoise Goddess), the lead ship was laid down at Toumachi Naval Arsenal in early 1910, after the launch of Aratama. She was launched in August 1912 and ultimately commissioned on July 21st 1914. A second unit, to be called Kuromegami, was reordered to an improved design in 1911.
Despite beign a formidable jump from the preceding Goryo class, ouclassing it in every category, Aomegami had been ultimately oupaced in the Battlecruiser race, mostly because of the lenghty building time of nearly 50 months. While having almost a comparable armor scheme to the British Lion Class, and even superior in some aspect to the Japanese Kongo Class, the main armament caliber had been superseeded by the 343mm and 356mm barrels of the British and Japanese ships. Even though she clocked at 27,9 knots during her trial runs it was still 0,6 knots lower than planned, leaving the crown of the fastest capital ship to Lion herself and the German Moltke Class.
Nothwistanding the fact that another slow construction schedule at Toumachi Naval Arsenal allowed other nations to surpass Kokoan attempted achievements, the Naval Staff was highly satisfied of the new ship. Aomegami Immediately replaced Aratama as Koko no Kaigun's flagship as soon as she was commissioned.
However, in spite of her marvelous lines and her initial popularity within the enlisted sailors, her career was nothing short of beign unlucky. World War I broke out just a week after the ship's commissioning. In Late August, flying her Flagships colours, Aomegami departed Kokoan waters to enforce the Naval blockade off Tsingtao. Here, on October 28th, she hit a German mine sustaining serious damage to the forward boiler rooms, necessitating her return to Koko for repairs. When she ultimately returned to service, basically all German naval forces in the Pacific Ocean had been defeated. Worse, her forward boilers never worked as reliably as they did before Tsingtao despite the repairs, causing the ship to not beign as fuel efficent as she was supposed to be. She thus saw no more Action until late April 1916, when Thiaria declared war on the United Kingdom. Following a request from the British -wich had problems mustering enough ships to deal with their new enemies- and fulfill its obligations under the Anglo-Japanese alliance, Aomegami joined her half-sister Kuromegami and the cruisers Hyoto, Gensho, Shinjima and Kitajima and departed for the Atlantic Ocean where they Joined a British squadron under the command of Rear Admiral Evan-Thomas. On June 25th, 1916 the joint Kokoan-British fleet and the Thiarian one clashed in the Battle of Tristan da Cunha. Aomegami soon developed boiler problems once again even despite she was not hit by a single enemy shell, causing her to fall out of formation. This had direct consequences to the ultimate outcome of the engagement, which saw the sinking of the Thiarian battleship LT Dunshayne and the brand new Kokoan Battlecruiser Kuromegami.
Reprising her role as Koko no Kaigun Flagship after the loss of her half-sister, Aomegami -still plagued by boiler issues- returned to home waters in October 1916 and saw no more action for the rest of the War. Superseeded by the newer Battleship Yagumo in December 1918, both by armament and as flagship, Aomegami entered the yards twice during the next three years. First she collided with a Japanese Merchant ship, sinking it, then her defective boilers needed an extra round of unplanned maintenance. In early 1922, after the Washington Naval Treaty had been signed, Aomegami was docked at Toumachi Naval arsenal for another refit, this time more thorough. Her main guns recieved canvas bags, training guns and 8-m rangefinders. The six anti-torpedo-boat cannons were landend and replaced with four high-angle 76mm ones. The searchlight platform were rearranged, adding an extra platform on the forward tripod. The bridge also recieved four enclosed lookout posts and a new rangefinder. A cap was fitted on the forefunnel to lessen smoke interference with the tripod platforms. Finally, the troublesome forward boilers were reworked once again, this time shiglty easing the fuel consumption issues. Neverthless, the Unlucky Goddess (fukouna megami), as she was nicknamed, still recieved some love from the sailors usually serving on her. As she was considered to have more elegant lines and held the seas much better than the new battleships.
The Naval staff also had plans to make the new vessel shine once again. A major refit was planned once the Battlecruiser Amagi would have been delivered from Japan, Initially by December 1924, then by early 1926 after delays caused by the Great Kanto Earthquake. However, nothing of this materialized, as the Goddess streak of misfortune met its end. While berthed off Fuyuki, just north of Toumachi, on October 13th 1925, a fire was discovered in turret 2 magazine. Before proper firefighting measures could be taken, Aomegami exploded at 9:26 in the morning. The Battlecruiser broke in two and sank rapidly taking with her 546 men of her crew. A subsequent inquiry found no definite cause, but it was highly suspected that improper storage and handling caused deterioration of the cordite cases, which ultimately led to their spontaneous ignition. Aomegami's wreck was partially salvaged between 1926 and 1927, and again in 1950-1958.
Ships in class: (laid down-launched-commissioned - fate)
Aomegami 1910-1912-1914 - Wrecked by internal explosion 1925
Kuromegami /-/-/ - Reordered to an improved design in 1911