YSS Ketsurui Yui, YB-05 (Originally GSS Ketsurui Yui, GB-05), was a Yuumi-class Battleship in Star Army of Yamatai (Grand Star Army).
In YE 24, during the Fourth Elysian War, it was heavily damaged in battle against the Elysians and crashed into the ocean on Yamatai (Planet), south of Karen's Lookout. It was named in honor of Ketsurui Yui.
As of YE 38, the wreck was cleared by the Star Army of Yamatai for recreational diving tours.