The Akashi is a repair ship under the command of Sango Sugimoto.
Converted from the pre-dreadnought battleship Asahi, the Akashi served as the primary repair ship for the vessels of Yokosuka Girls' Marine High School. She's often seen with the supply ship Mamiya and her destroyer escorts Hamakaze and Maikaze.
Due to its nature as a repair ship, the Akashi has a larger complement of students performing mechanical works on vessels. The ship can also carry spare parts, especially fresh main guns, and install them in a matter of hours.
The Akashi also has a small complement of cats on board. They've been instrumental in preventing the Totalitarian Disease from spreading into the ship.
Over the course of the events of Haifuri, the Akashi and her support fleet were untouched by the Totalitarian Disease. This is due in no small part of the cats on the ship, which hunted down the rodent carriers.
Principal Mayuki Munetani, believing in the Harekaze's innocence, sent the support fleet to rendezvous with the destroyer. The fleet's presence alarmed the Harekaze crew, seeing this as the fleet to take them to custody. An infected Tama manned an anti-aircraft gun aboard the Harekaze and began firing on the Akashi and Mamiya. Fortunately, nobody was hurt and the ship suffered little damage.
Soon, the Akashi began supporting the Harekaze on its mission to save the infected ships. It provided fresh upgrades to the Harekaze's main guns and fire control systems.