The Sarushima is a modified Independence-class Littoral Combat Ship (LCS), serving as an instructor ship at Yokosuka Girls' Marine High School. Instructor Kaoru Furushou is the vessel's commander.
Like the mainstay of the Blue Mermaids' navy, the Sarushima features a trimaran hull, designed for speed, maneuverability, and stability. Forward of the bridge is a modular section capable of holding various weapon systems such as anti-ship missiles and VLS units for multi-mission capability.
It features a helipad, possibly designed for Blue Mermaids drones as heavier-than-air flight doesn't exist in the Hai-Furi universe.
Instructor Furushou led the training vessels, which included the Kagerou-class destroyer Harekaze and the Yamato-class battleship Musashi, on a two-week maritime exercise at the Nishinoshima New Islands. At the same time, it transported a research team en route to the islands to study local marine ecology (although it was soon found out that their real intention was to salvage data from a surfaced lab submarine).
While waiting for the Harekaze and Musashi, which lagged behind possibly due to engine trouble or navigation error, the Totalitarian Disease got into the Sarushima, infecting the crew.
The Sarushima met the Harekaze on the open waters near the islands and began opening fire with its main gun. At this point, the Harekaze crew was unaware that a virus had gotten to the Sarushima crew, including Furushou. The Harekaze retaliated by firing a dummy torpedo, which hit the Sarushima port side.
After sending out a distress signal to the mainland, Furushou lost consciousness. The Sarushima was towed back to the mainland for repairs, while Furushou, the crew, and the research team were taken into custody for the incident.
Furushou was later released to take command of one of the Sarushima's sister ships, the Tenjin, during Operation: Perseus.
- Alert viewers during Episode 1 will notice the Sarushima's main gun changing. Since Mashiro stated that the main gun has a rate of fire of 22 rounds per minute, this may refer to the Mk.45 Mod 4 127mm/L62 naval gun, as the Mk.110 57mm can fire 200 rounds per minute.
- The ship may be named after Sarushima ("Monkey Island") off the coast of Yokosuka.
- A World War II-ship named Sarushima existed but as a Natsushima-class minelayer.