Sai was assigned to join Team Kakashi and assist in meeting with a Sasoriís spy who worked for Orochimaru. Danzou tasked him with a secret mission to gain Orochimaruís trust, locate and assassinate Sasuke. Upon meeting his new teammates, in attempt to seem sociable, Sai questions Narutoís manhood and insults Sasuke, which results in Sakura punching him. He tries to look more caring by smiling, although due to his obvious insincerity his teammates dislike it. While moving on to the meeting spot, Sai wonders why Naruto is loyal to a traitor like Sasuke, and Naruto responds to that by saying he's not a traitor, but rather a friend. After spending some time with Naruto, Sai becomes friendlier towards others and starts to appreciate bonds.
Having been orphaned as a child; Sai has been recruited into Root, a secret ANBU branch, where he was trained to be emotionless. In his early life, he became friends with another Root member, Shin, whom he eventually considered a brother. Sai was also a talented artist and had an art book in which he illustrated his ninja growth and feelings in one half, and his brotherís in the other. Later, Shin died due to an illness, which resulted in Sai completely shutting down his emotions. During this period, Sai has been sent on various highly-ranked missions, mostly involving assassination of foreign ninja. Even Danzou himself considers him the strongest of his generation.
Sai's most notable talent is his art, and he claims to have drawn thousands of pictures. His artistic talent is also the source of his main jutsu, known as the Super Beasts Imitation Picture, where he infuses his chakra with the ink to bring his drawings on a scroll to life. Sai is fairly skillful in taijutsu as well.