Terai is a former member of the Root group (under ANBU). As a member of Root, Terai, like Sai, was trained to be a ninja with no affection, no relatives, and no name of his own. The goal is for you to be able to complete the task better. Although the organization was later officially disbanded, Terai remained loyal to its leader – Shimura Danzou.
Shin was an orphan of Konohagakure who was later recruited into Anbu’s Root division. Despite being trained to be emotionless, Shin is still close to another Root member, Sai. Shin recognizes Sai’s artistic talent and convinces him to pursue his hobby. Sai considers Shin as an older brother, but later Shin dies for unknown reasons. According to Sai, Shin and Naruto very similar, Shin is also loud, impatient, and unrefined. However, Shin is also a kind person with a pleasant personality, as he helped Sai pursue his passion for drawing. Shin is also a very resilient person.
11. Yakushi Nonou
Yakushi Nonou is a nun who helped an orphanage. But before that, Nonou belonged to Root – an organization affiliated with ANBU and was an expert on intelligence. She left the organization to work at an orphanage. Nonou finds an injured child near an abandoned village, that is Yakushi Kabuto and brings him back to raise him at the Konoha Orphanage. She is also known as “The Walking Maiden”. Although they are not real mother and daughter, Nonou and Kabuto have similarities. Yakushi Nonou can use Doctor Ninjutsu to heal the wounds of the ninjas who fought in battle. Danzo has said that there is no one with similar abilities and intelligence like her and that she will not lose her mind or ally with the enemy. However, Nonou also has a hard time getting rid of her personal feelings, so she is not suitable for Root.
Source link: Geniuses who make enemies afraid of “losing secrets” in Anbu – Naruto (P.3)