Seiichiro Tatsumi

An accountant until he died at 29 and became a Shinigami, is the secretary of the Shokan Division. He spends most of his time going through paperwork and working behind the scenes. He was Tsuzuki's third partner, and worked with Tsuzuki for three months but, unable to cope with Tsuzuki's pain, quit. Tsuzuki reminds Tatsumi of his well-born mother, who constantly grieved despite Tatsumi's attempts to take care of her. Tatsumi eventually killed her (or at least blames himself for her death), and the crime still haunts him.

source : http://en.wikipedia.org/wiki/Descendants_of_Darkness#Seiichiro_Tatsumi