Котецу Ісане

Isane Kotetsu, is the lieutenant of the 4th Division, the medical and supply relief division, in Gotei 13 under Captain Retsu Unohana.

Isane is the older sister of Kiyone Kotetsu, one of the two 3rd seats in the 13th Division. Unlike Kiyone, she is generally quiet and observant, though she shares her sister's sense of loyalty. She looks to Unohana as a mentor and mother figure. It is noted by Unohana that Isane suffers from frequent and recurring nightmares.