Sakura ends up needing half a day to extract all the poison from Kankuro. Then she needs an additional day to create an antidote for the little poison still in Kankuro's system. And to create antidotes for them as well. Annoying, but Sasuke can't deny the advantage the antidotes will give. Aside from what she makes for Kankuro, she has enough ingredients to create an additional three doses, each of which will protect someone for three minutes.
Three minutes in battle are an eternity. Sure, Naruto would just burn through the poison, and Sensei might be able to get rid of it as well, but they'll still be hampered enormously until their healing factor takes care of it, if not completely incapacitated. Same with Sakura. She can negate the poison enough to keep it from killing her, maybe even get in another attack or two, but no more.
As for him, well. If he gets hit with that poison, it's game over. Good thing he specializes in dodging.
But yes, the antidotes offer a huge advantage. Doesn't mean he has to like the time needed to make them. At least Naruto's eagles mean they won't lose too much time catching up to the summons he sent out to track Gaara.
Naruto sent out a variety of summons. There was Nezumi the rat, who got paired with a horse, Matsukaze. She's there for Nezumi to ride on. Nezumi can't move as quickly as he needs to for a mission like this. Then there was Bikou, the lightning wolf from their spar, Sasayaku, a moth Naruto has mentioned in his letters, and finally, Ku, Ka and Mon, three bears Naruto conspicuously hasn't mentioned before.
Naruto didn't send out any of the pack. He doesn't want to risk Kakashi needing them and them being unable to respond to his call.
After Sakura finishes preparing the antidotes, she needs to rest. The rest of them took naps to ensure they'll be in top shape when they set out, but she didn't have that luxury. She can still keep going of course, but against S-class opponents, even the slightest bit of fatigue can turn fatal.
Fortunately, Naruto's eagles take care of this problem as well. Not having to travel by foot really is incredibly useful.
Sandamaru is less than pleased to be called again, though.
"How dare you treat me like one of your spineless sycophants. I am not your lackey."
"Are you including me in that statement?" Hime asks and Sasuke is pretty sure that she's amused. He's definitely sure that Sandamaru, his feathers flaring and his head swiveling towards Hime, did not mean for his remark to be taken that way.
"No, of course not, Hime, I would never – I meant all those other cretins he consorts with, not you. You are as untameable as the wind."
Strong words from someone who can, in fact, tame the wind.
Naruto jumps into the conversation and, with the ease of long familiarity, butters up Sandamaru by saying he only summoned him because mountain eagles are the fastest flyers there are. None of his other flight summons capable of carrying them, a bat and owl respectively, can get them to their destination as quickly as Hime and Sandamaru can. Sandamaru grumbles some more, but despite his complaints, he doesn't dispel himself or object when Yamato-sensei and Chiyo get on his back.
Because the Honorable Chiyo is going with them. Now that was an unpleasant surprise. Temari was originally supposed to come instead, but she's needed at the borders. Baki didn't share more details of course but Sasuke is pretty sure that the news of Gaara's kidnapping has reached Iwa. It's the most likely explanation for why securing the borders takes priority anyway.
He, Naruto and Sakura get on Hime's back. Naruto's summons haven't tracked down Gaara yet, but they're on the trail, and they've informed Naruto of the direction they're traveling in. Namely, towards the Land of River.
Sakura, taking the opportunity to get some sleep, gets comfortable against him. She could have used Naruto as a pillow instead, but given that Naruto can get a message from his summons at any time, Sasuke is a better choice to keep her steady while they travel.
Even with the mission, the opportunity is too good to pass. Sasuke gives Sakura, huddled into his side and already fast asleep, a pointed look before he smirks at the idiot. Seems Sakura prefers to cuddle with him over cuddling with Naruto.
Naruto responds by sticking his tongue out. Sasuke grins.
As they fly, Naruto gets updates from his summons. They can't send him true messages, but they can send chakra pulses along their connection, meaning they can send coded signals. Like coordinates.
Most of the coordinates are coming from the bears. Naruto isn't surprised by this. In his words, bears are crazy good at tracking, seriously, never piss off a bear. They hold grudges like whoa and they will hunt you down. There's a story there. Given that Naruto hasn't shared it in his letters, it's a hilarious one. Something to wheedle out of him after the mission is over.
When they start nearing the border, Sasuke wakes Sakura.
It's a good thing he does. Shortly after they cross it, Hime lets out a piercing cry, making him activate his Sharingan on instinct and he sees - Naruto and Sakura startle, turning combat ready on instinct - Hime, alarmed and caught off guard and preparing to dodge an attack!
"Incoming!"
His yell goes out right before Hime finishes tucking in her wings.
They drop like a stone and the change in angle lets him see - chakra infused paper, all pieces part of the same whole. Transformation technique - their attacker.
The paper follows them down. The pieces are - reinforced with seals, resistant to fire, water and lightning. Carrying an object in its center mass - moving faster than Hime. Hime - knows this too - creates a whirlwind with another piercing cry, the attack aimed at their pursuer.
The paper slices through the winds - precise bursts of wind chakra, countering the vortex - weakened but not stopped. When Sandamaru sends a stronger whirlwind from the side, Sasuke throws shuriken and wire, taking advantage of the wind currents to get his weapons around the object being carried. The object is - long, thin, inflexible. Protected by a significant amount of chakra - important to whoever it is that's attacking them. They're planning to do something with it. Sasuke does not want to find out what.
Paper shoots out, catching his shuriken and slicing through the wires. The object and most pieces keep chasing Hime.
Hime - is rapidly moulding chakra - snaps open a wing and spins up - partly disorientating Naruto and Sakura - before she uses her other wing to create a whirlwind that makes Sandamaru's look small.
The paper gathers around the object and prepares to withstand an attack, and the outer pieces - light up, chakra infused ink becoming visible - hold more than resistance seals!
"Bomb!"
His yell gives the others a split moment warning before the explosion tags go off.
The explosion - partly dampened by a rushed wind manipulation from Hime - manages to almost knock them off Hime, and Sasuke almost doesn't process - paper surging through flames - the follow up attack in time. He leaps towards their attacker and - avoids the cuts aimed at vital areas - slices through the paper with his saber but there's too many and the object manages to pass him, and Naruto and Sakura are still recovering from the explosion and they won't move in time!
"Jump!"
They jump.
The object follows Naruto. Sasuke hurriedly taps Sakura with his Sharingan and prepares a replacement but he already knows - speed, angle, velocity - they won't be in time.
Sasuke casts his technique as the paper releases the object - cylindrical chakra construct - and Naruto is - not fast enough - trying to dodge and then Sasuke is switching places with Sakura and he's flying towards Naruto and slicing his saber at - paper in a different shape. Human, female, wearing a ring like his brother - the hand holding the construct but he's too late.
The chakra construct is jammed into the Kyuubi's seal.