The YSS Jikogisei, meaning “self-sacrifice”, was a Hayai-Class Gunboat renamed and temporarily reassigned to the Seventh Fleet in late YE 33 for a single secret mission. The craft was actually a wrecked Hayai from another fleet with irreparable frame damage, repaired with parts which had been removed from other craft for being outside tolerances or having operated in service beyond their stated time limitations. The Jikogisei was thus a one-use-ship which did not deprive the Star Army of resources, never even having had a Seventh Fleet registry number assigned to it. The areas on the hull which once held the registry numbers of the former fleet had been blackened by weapons fire, making it unnecessary.
The first and only mission was with Chui Blues Arnoul(Kage Yaichiro in a new body in disguise) as its only crew, on a mission to the Xylar system to determine NMX fleet strength, during which it and its pilot would be destroyed by a craft repainted in IWL colors in part of an infiltration scheme. When the NMX utilized a captured Star Army Fortress, however, the craft instead was used to damage the Star Fortress' Production Bay by self detonating, and taking out an array of battlepods with it.
In this way, the Jikogisei was sacrificed, but met a noble end in combat damaging the enemy rather than being unceremoniously decommissioned.