IKS Roku

The IKS Roku was a Klingon Defense Force bird-of-prey in the late 24th and early 25th century. In 2390, it was under the command of Captain Yogh, and in 2410, Captain Zang. It was in service of the House of Groth. 

History
In 2390, the Roku surprised the USS Phoenix (NCC-65420-X) with an undeclared dissolution of the Federation-Klingon Exchange officer program aboard the Federation ship, and allowed Klingons to defect and beam over. ("Into Harshness")