A servant to Yagyu Jubei who walked the Earth for 300 years searching for a worthy successor to his master. Besides the Lovely Eyepatch, he entrusts Jiyu with his master's sword and the "Koinosuke Whistle" that summons him. Though mostly a comedic relief character, Koinosuke is good-hearted and does his best to serve both his old master and his new hosts.
*Wikipedia*