Kugi (釘, Japanese for Nails) is an Instructor at the Yuengiri Academy, well-known for his drill-sergeant-like attitude and ability to bring forth ones talent. He is a skilled practitioner of the Yuengiri arts, as well as the Shinigami arts. He is known alternatively by the nickname given to him by his students, which is Hard as Nails. Following the death of Rikimaru Ichinose, Maki Zhijun elevated Kugi to the rank of Lieutenant, for he was already a member of the Seventh Division. He ties with Tyrell Nishiki and Zero Ukitake as the only lieutenants capable of performing their Bankai release.