Tsukubo-class battleship (FT)

Both Tsukubo-class battleships were laid down as Akagi-class battleships in the New Greater Empire, with the first vessel having been launched as Nagasaka in 186, the second vessel launched as Sudazan in 194, and the third vessel as Odaka in 194. All three vessels completed multiple tours of duty with the Imperial Navy before being decommissioned due to damage in the Second Hyperpower War. The vessels were stripped of all essential components and weapons and their hulls were sold for scrap. At some point, the three scrapped hulls were purchased by a third-party shell corporation linked to the Imperial Frontier, and the hulls were transported to Daitetsu between 231 and 235.

From 235 to 242, two of the ships were rebuilt and refitted by the Imperial Frontier in the Daitetsu Imperial Shipyard, with the third cannibalised for parts. Though there was some concern in the Empire and the Confederation of Coreward States regarding the rogue state's acquisition of space warfare capabilities on par with the Akagi-class, it was eventually determined that the two battleships produced would assuredly be of inferior quality due to the Imperial Frontier's lack of technology and the damage that the hulls had already sustained in the war. In 242, both ships were commissioned into service with the Imperial Frontier Navy, and were unveiled in a propaganda video. This was also the first time that the largest modification made to the ships, the addition of a ventral capital-class mass accelerator cannon, was revealed to the rest of the Human Sphere.

Besides the mass accelerator guns, the exact armaments of the Tsukubo-class ships are still unknown due to the Imperial Frontier's secrecy and the Tsukubo-class ships rarely departing from Daitetsu. For strategic planning purposes, it is assumed by Confederate military officials that the ships are at least on par with Akagi-class vessels, though it is almost certain that their weapons systems are inferior to the mainline Akagi-class ships. Their sensors, targeting systems, and electronic warfare capabilities are also unknown. Some analysts have also suggested that the Tsukubo-class ships may only be armed with the ventral mass accelerator, which is by far the most dangerous weapon in the Imperial Frontier's arsenal.

The ventral mass accelerators, adapted from orbital defence guns, are calculated to be able to destroy essentially any warship currently available in the Human Sphere with a single shot, as well as cause major surface devastation on par with multiple thermonuclear weapons if fired at a planet. However, experts strongly believe that the Tsukubo-class vessels lack targeting systems capable of firing these guns at anything other than a stationary target, making them useless in space combat, but still capable of severe devastation if fired at a planet. Due to the threat these weapons pose to population centres, both the Empire and the Confederation have declared the two Tsukubo-class vessels as mobile weapons of mass destruction and make efforts to track their locations at all times.