Ōko Yushima (由嶌欧許, Yushima Ōko) is a Shinigami of the 12th Division and worked in the Shinigami Research and Development Institute. He was the developer of the Mod Souls.

Yushima bears a great resemblance to both Nozomi and Kagerōza Inaba, having long green hair and brown eyes, but no yellow hair and a more narrow jawline with less-define cheekbones. During his time with the Tenth Division, he wore the standard Shinigami shihakushō. After he was transferred to the Twelfth Division, however, he donned a long yellow robe that buttoned up in the front and protruded upwards from his neck, covering the entirety of the back of his head, in the same fashion as Kagerōza Inaba's attire

(Source: Bleach Wikia)