Koga Senryu (高杉 晋作, Senryu Koga) also known as K (ケイ, Kei) is a shinobi from Kumogakure and a Jonin-Rank ninja. He is the current Jinchuriki of the Eight-Tailed Giant Ox and like his predecessor Killer Bee, has gained complete control over it, making him the only known Jinchuriki alive to have tamed their inner beast completely. Known throughout the shinobi world for his mastery of Lightning release techniques, he is mostly referred to as Kumogakure's Lightning Beast of Flash (雲隠れ派手な雷獣, Kumogakure Hadena Raijū) by the other 4 great shinobi nations.