Naki

ナキ

Naki is a ghoul who was held in the CCG's ghoul prison ward before the Aogiri Tree invaded the facility. The Aogiri Tree broke him out of jail because he was a direct subordinate of Yamori and supposedly his right-hand man.
Naki is portrayed as a confident individual, boasting about his strength and his status as Yamori's right-hand man. Like Yamori, Naki displays a twisted mindset; although he is not as cruel as Yamori, he shows his personality permanently without any effort to hide it. While impulsive and easily irritated, Naki is depicted as very emotional and trusting, perhaps to the point of naivety. He holds Yamori in high respect and was devastated to learn that Yamori had been killed while the Aogiri Tree was breaking him and other ghouls out.
Naki has a childlike personality, believing that helping Yamori with counting money and running errands makes him a responsible person worthy of others' respect. He views loneliness as the most painful experience, and as such, he risks his life to protect his comrades so they never feel the loneliness he experienced when he was released from prison only to hear that Yamori had died and left him alone.
He also seems to have copied Yamori's habit of cracking his fingers (although he cracks his middle finger instead).