Sarada doesn't have a single memory of her father; she only knows his face from an old photograph from before he left the village again. And, as if that's not enough, the family portait is actually a picture of Team Hawk with Sakura's photograph overlapping Karin.
Sarada had been asking Sakura about Sasuke, wanting to know if he ever wore glasses like she (Sarada) does; Sakura only offers vague answers as she tries to hide Sasuke's defection from the village, angering Sarada and fueling her suspicions about the legitimacy of her parents' marriage. Then, she sees the picture of the bespectacled Karin and starts wondering how much of what she know about her family is true.
And it gets worse, if that's even possible. We see only the picture of team 7 (taken before Sasuke first left the Leaf) and the "family portait", implying that Sasuke didn't take a single photo with his wife and daughter before he left.
On a more basic level, just seeing how bitter and cynical and sad Sarada has become as a result of her dysfunctional family is just awful, something which is only made worse when we see her openly break down into frustrated tears near the end of the first chapter. The Uchiha princess is a very human, very sympathetic character for all of the most tragic reasons - reasons no teenager should ever have to deal with.
And just to add to the sadness. When Sarada presses Sakura for answers about her father. She gets so mad she Megaton Punch the ground. Not only scaring Sarada, but also causing her to cry in fear. Her mother refuses to tell her about her father and was essentially threatened to stop.
Sakura is as hurt and lost by Sasuke's absence as her daughter. Despite her Megaton Punch being a horrible overreaction, it's a sad reminder of how people in general lash out under immense stress (and her face in the immediate aftermath looks completely dejected). It's even more jarring considering Sakura's ground-breaking strength used to be played for laughs.
The boy with the Sharingan speaks in a halting way, pausing between words. Kakashi suspects he might be one of Orochimaru's test subjects. Whoever he is, he seems to be nothing but a tool to the Big Bad.
Boruto arrives at the village gates to find that Naruto already left, since he had a bad feeling about the situation (which was entirely accurate, as it turns out). It may be a crisis, but Boruto takes it personally, even though Mitsuki, Sarada and Shikamaru think he's overreacting.
After Boruto denies Sarada's request, she finally snaps and tells him that if she were in his place, she'd gladly run after her father to give him the lunchbox her mother made with so much care and love. Considering her family situation, it's little wonder she considers Boruto stupid for not appreciating what a great family he has. Sure, Naruto may not be around as much as his son would like, but at least he's there and he tries, something evident by their training session just a couple of days ago.
Now, this isn't a sad moment per se. When Naruto pats Sarada's head and declares she has nothing to fear while he's with her, Sarada blushes and has this trembling little grin, like she's trying very hard not to cry. It's a realy kick in the gut to see a small gesture like that have such an effect on the little girl. In that short trip from the village to the tower, she forms a greater bond with Naruto than she ever had with her father.
At the end of the chapter Sarada finally meets her dad Sasuke, expecting a heartfelt reunion and maybe even a hug. He notices her Uchiha crest and Sharingan and draws his sword on her, asking if she's an ally of the white-haired boy who attacked him. He doesn't recognize her at all.
Sasuke finally recognizes that he actually has drawn a sword on his daughter. The look of realization on his face is terrible.
Sasuke: "Sarada? It's... it's really you?"
In one panel, we see Sarada's Imagine Spot of getting a hug from her father fading away. Her hope of getting a heartfelt reunion is nothing more than a shattered dream.
Sasuke is visibly distraught when Sarada asks why he's never around. He can't say anything, lest he compromises his mission, though his cold response to Sarada doesn't help.
When the tower is attacked, Sarada moves closer to Naruto for protection. But she doesn't move behind him like an inexperienced ninja would get behind their sensei. Instead, she grabs hold of his clothes the same way a scared little kid holds onto a parent and clings tightly until they feel safe again. Somehow, that's incredibly sad: she just met her father but still feels closer to Naruto.
When Shin Sr uses Sasuke's previously marked sword to wound Naruto, Sasuke and Sarada look horrified.
Sakura and Sasuke both look deeply saddened as they realize how much pain their poor communication had caused their daughter. Sasuke also realizes that his lack of presence in their lives has put not only his daughter in a bad place, but his wife as well.
Sarada's worst fear has been verified: The DNA test shows that Karin's DNA sample is a match to hers, so Karin is her real mother, not Sakura. Poor Sarada looks completely devastated after that.
Naruto and Suigetsu are also shocked by the reveal. Suigetsu wonders if he did the right thing by helping her, while Naruto is at a complete loss for words.
To pour salt in the wound, the warmth between Sarada and Naruto is completely snuffed. She accuses him of lying to her, which makes it tragic as Naruto was completely unaware of Karin being the real mother as well. Though these later turn out to be false fears - Sakura is Sarada's mother - the fact that everyone even questions it shows that even after all that time, they still can't completely trust Sasuke. Meaning that Sasuke hasn't been reassuring enough to his allies, closest friends, and family.
The chapter ends with Sarada's Sharingan flaring up, her eyes filled with sorrow and anger in stark contrast to the hope and joy when they first awakened.
Naruto still remembers how horrible his childhood was. From the look on his face, the memories still hurt. Even though this wound healed a long time ago, the scar remains.
Even though Sarada has every right to feel confused and betrayed by the misinformation, her swiftness in turning on Sakura is heartbreaking. Sakura is the only consistent, stable, loving parent Sarada has ever known, and just like that, Sarada is willing to turn her back on her. Not only does this show her pain, but also how the Uchiha tendencies to be tortured by and subsequently sever bonds are alive and well within her, and can only worsen if her family continues to be distanced like this.
Shin Sr tries to use his clones/children as a distraction in order to escape. The kids, however, beat him to it and stab him with their weapons, using his own cold logic about "evolution" against him. Now, there's a fine family.
Even though it's Played for Laughs, there's something very sad about Sakura leaning forward to get a kiss from Sasuke, and Sasuke blowing her off. You can tell how much she's missed her husband, even though she tries to be strong for Sarada, and he won't even give her a kiss goodbye. And knowing that Sakura has loved Sasuke for most of her life... All her love for him, and he still won't give her the emotional warmth she likely craves from him.
While Karin has matured considerably, it's sad to see that she might still have some feelings for Sasuke. Her acceptance that he's happy with Sakura is beautiful, but you really wish the girl would find someone (*cough*likeSuigetsu) so she can be in a happy relationship too.