Tatsuji

was an ANBU, working in Konohagakure until the day he was lost on a mission.

Twelve Guardian Ninja Arc
He was later found by the ANBU Black Ops with Danzō Shimura. He was supposed to give him information, but was a double agent for years and got the Konoha elders Homura Mitokado and Koharu Utatane information from Amegakure before Tsunade can get Ibiki Morino to torture him.