Tenchi Bridge Reconnaissance Mission Arc
In Sai's first meeting with Team Kakashi, he exasperates both Sakura and Naruto. Sakura quickly compliments how Sai looked similar to Sasuke and upon returning back with Naruto, the latter comments how they were alike in looks but completely different people based on personality wise.
On their way to meeting Sai again, he aggravates both Naruto and Sakura by insulting Sasuke's name. Naruto stands up for him, but is stopped by Sakura to where she apologizes in his place. Only then, Sakura reveals a fake smile before sending Sai off as she punched his jaw. Sai quickly takes in that even Sakura can "fake a smile."
Upon the battle between Naruto and Orochimaru, Sai tries to leave to begin his "real" mission as his teammates struggle to deal with Kabuto and the Snake Sannin. All the while, Yamato and Sakura desperately try to calm a Naruto who has fallen into his tailed beast form. During the process, Sakura is injured and falls off a cliff to where Sai simply ignores as he continues to fly up. Yamato is then forced to save her instead.
As Sakura regains consciousness, the team turns to leave in order to recover. Naruto and Yamato separate themselves as they talk about a way to save Sasuke, Sakura on the other hand goes through Sai's belongings and finds a sketch book. Inside the book contains the sketches of Sai and his "brother." Skimming through the pages, Sakura is found astonished as she finds that they were the very sketches of the experiences that Sai faced. Later, Sakura and the rest of the group find out that Sai is actually a spy who is hunting Sasuke. Once Sai finds Sasuke's room, an explosion occurs. Spotting Sai up above, Sakura runs up to him and prepares to attack. Stopped by Sasuke's appearance, Sakura later stands alone as she watches her teammates clash.
After sometime upon returning back to the mission, Sakura spots Sai who is shown drawing by himself. Curious, Sakura sneaks up and watches from behind. Surprised by such skill and his about him having a more "human side". Upon realizing his lack of communication skills, Sakura invites Sai to come with her to meet Kakashi. Before leaving, Sai expresses his newly found knowledge and calls Sakura "ugly". After shrugging it off, Sakura and Naruto decide to introduce Sai to Team 10. To their surprise, Sai quickly comprehends with his new friends as they go out to dine.
Upon collecting the data he gathered from Sakura, Sai concludes that women do not like to hear how they really are and that it would be best to say the opposite of what he truly thought. Being introduced to Ino, Sakura mutters a simple warning Ino about his poor communication skills and to not be betrayed by his looks. When giving nicknames to the group, Sakura snickers at the thought of hearing him call the Yamanaka "ugly". However, Sakura is dropped in dismay when he instead calls her "beautiful."
When Naruto learns that he has wind chakra, he is sent to train with Kakashi and Yamato. Knowing that Naruto is going through hard-training, Sakura comes and watches him from time to time to cheer him on. In the anime, Sakura is standing under a tree as she takes shelter from the rain. Sai who comes out of the bushes creates an Umbrella as they stand side by side.
Akatsuki Suppression Mission Arc
Sakura and Sai return back to Konoha from their mission. As Sakura offers to help an injuried Naruto eat, they are interrupted by Sai (along with Kakashi). Later, the trio is met by Konohamaru who show's them his variations of newly found Sexy Techniques. Sakura who finds it disgusting disregards the jutsu. Furious with her comment, Konohamaru reveals his Boy on Boy Technique which reveals a one on one action of Sasuke and Sai. Excited by such scene, Sakura is looked upon by her teammates in disgust, but ironically Sai simply replies; "Oh, it's me and Sasuke."
Five Kage Summit Arc
After the news of Sasuke began to spread, Sai confronts Sakura about Naruto's feelings and guilts trip her in the process. Later, Sai accompanies Sakura along with her team to track down Sasuke.
Before Sakura leaves, Sakura confronts Naruto and makes a fake confession as Sai and the group watch in disappointment. When her confession is disregarded, Sakura leaves without notifying the team about her plan. Sai knowing this creates an ink clone to inform Kakashi and Naruto as Sakura and his original self leave to track down Sasuke.
When the group starts to near Sasuke, Sakura tries to set off a knock-out gas to incapacitate the other members. But before she could do so, she is stopped by Sai. As Sai stops her, he confesses that he had told Naruto and Kakashi about their plan and they should wait for Kakashi to arrive. Sakura then convinces Kiba and Lee to fight with Sai then using the knock-out gas as they began to scuffle. As the real Sai is knocked out, the ink clone quickly disperses as it warns Kakashi about Sakura's actions.
Fourth Shinobi World War: Climax Arc
After asking Jūgo about Sasuke's true motives he asks Sakura if she trusts Sasuke fore he doesn't. Sakura replies saying she's happy that Sasuke is back and she trusts him. Sai then notes that her words may seem sincere, but her smile is fake.
The Last: Naruto the Movie
Naruto, Sakura, Shikamaru and Sai try to get into the moon’s barrier save Hanabi and stop Toneri and Hinata's wedding ceremony. The team split up into two team once they are inside the castle. Sai and Sakura went to find and save Hanabi while Shikamaru and Naruto went to stop the wedding.
- Sai is able to see through Sakura's continous fake smiles
- Sakura is shown to admire Sai's art
- Both respectively admire the other's skill
Sai to Sakura - Chapter 286:
- "A smile can get you out of a tough situation.. even if it is fake."
Sai to Sakura about Art - Chapter 287:
- "I've drawn hundreds, maybe thousands of pictures so far...other pictures have the situation at the time, and the artists feelings...like protraits have the person's name... but don't pictures usually have titles...? To be more precise, even if I try to give them titles, I just can't do it. I don't feel anything.. they don't put me in mind of anything..."
Sai about Sakura - Chapter 635:
- "Your words might be sincere... but... I know your smile is fake."
Databook 3 (Sakura Haruno's Profile):
- "Sakura entertains complex feelings towards Sai, who was assigned to Team Kakashi as a replacement for Sasuke. Acknowledging Sai as a team member means acknowledging Sasuke's absence. But following Sai's evolution, Sakura learned how to bond with him as well."
Databook 3 (Sakura Haruno's Profile):
- "Sakura is also the one who immediately found out about Sai's complex personality."
Among the Fans
SaiSaku is a somewhat popular couple in the Naruto fandom. It seems to had gotten somewhat popular and it was supported ever since the umbrella moment Sai and Sakura shared while watching Naruto practice his RasenShuriken. It is a rivaled by SasuSaku, NaruSaku and SaiIno.