As soon as Yuna appeared before him, the human-looking person with a huge plant around his head had a very strange feeling about her. Or rather, it would be more correct to use "they" for the half black and half white humanoid since they are composed of two different entities, Black Zetsu and White Zetsu.
Black Zetsu was only slightly flustered by Yuna's presence. He was the manifestation of someone's powerful will, so this was the first time he met someone with an even more powerful will. He, of course, didn't know why Yuna's presence made him this flustered.
White Zetsu on the other hand was absolutely terrified of Yuna. Due to various reasons, he was very closely connected to nature and the world itself, but Yuna's very presence seemed to reject all of it like she wasn't even a part of this world.
Although Black Zetsu was only slightly flustered at the start, that changed when Yuna demonstrated her flying sword slash that ignored Obito's Kamui. Black Zetsu considered himself to be pretty much immortal since he wasn't a real living being from the start. He could freely change his form and even if someone were to cut him into pieces, he could easily regenerate himself.
Yuna's sword strike, however, gave him a feeling of dread. He wasn't sure how and why, but he felt like that sword strike could actually kill him, which meant that Yuna was a genuine threat to him.
How would someone who never felt genuinely threatened for a very long time react, when he was suddenly in danger?
"O-Obito, we need to retreat for now. She is more dangerous than we anticipated."
The person would try to get away from the threat. Black Zetsu was given a very important mission and he saw no reason to risk his life here. Especially not against someone who he was in no hurry to capture. Even if they managed to overpower and capture Yuna, all they could do with her, for now, would be imprisoning her, which was a huge risk on its own.
Obito, who just managed to get out of his stupor looked at the Zetsu duo in bewilderment.
"What do you mean by "retreat"? How could we possibly retreat, now? For some reason, she knows my actual name, and we can't be sure of how much of our conversation she listened to either. Additionally, she is already very strong and her strength will only improve in the future. We need to get rid of her as soon as possible."
Before Zetsu could answer him, a deafening roar echoed over the whole area and moments later a gigantic beast with three tails appeared near the village of Kirigakure.
After seeing the Sanbi appear in the distance, Yuna clicked her tongue in annoyance.
"Sorry to disturb your lovers' quarrel, but I promised that I will be defeating the Sanbi and I never break my promises, so I got to go now."
Obito immediately scowled when he heard Yuna said that she will leave like it was no big deal.
"Do you really think we would just let you go like that? This is the perfect chance to get rid of you, so there is no way I will allow you to leave."
"You truly are delusional, aren't you? You? Stopping me? What a joke. BUT, I am someone that loves a good joke, so I will permit you to give it a try. Instead of instantly leaving with Minato's [Flying Thunder God Seal], I will give you a total of ten seconds to entangle me in combat. If you reach me, I won't be leaving. Aren't I nice?"
Obito instantly crouched down and prepared himself to attack Yuna, but just before he could jump forward, Yuna lifted her sword with two hands, and the moment the tip of her sword reached the highest point it felt like someone was holding a blade to Obito's and Zetsu's neck. While Obito's body was instantly doused in a cold sweat, Zetsu's was shaking in fear.
"I, of course, will try to prevent you from doing so. Rejoice, for this is the first time (in this life) that I am using this technique."
"[Ice Sword Combination Style: One Slash Begets a Thousand Cuts]"
Yuna slashed down her sword, resulting in a massive cut made out of ice to fly at Obito and Zetsu, and moments later, it started split apart again and again, until it was no longer a single big slash but thousands of small ones, which created a massive wall of deadly attacks.
Seeing the massive wall approaching him, Obito felt like death was creeping closer to him by the second, so without a moment of delay, he started forming hand signs and moments later he smashed his hands on the ground.
"[Wood Style: Wood Dragon Jutsu]"
A massive dragon made of wood appeared out of the ground and charged into Yuna's attack, but the moment it came in contact with it, the dragon was simply shredded to pieces while barely slowing down Yuna's attack.
Just before Yuna's attack could make contact with Obito, Zetsu regained control over his emotions and used the same jutsu as Obito to slow it down some more, and just like with Obito's wood dragon, Zetsu's was torn to shreds like it was nothing.
Obito gritted his teeth when he saw that and then he realized that there was nothing more he could do, so he simply crouched down, while trying to protect his head by crossing his hands in front of it.
Yuna, meanwhile, looked at the duo with some interest in her eyes. She did not expect that both of them would be this proficient in wood release. Although she doubted that those two actually noticed it, the spot in her attack where the two wood dragons hit, was actually weakened quite a bit and Obito might actually survive it.
Although Yuna found it a bit of a pity that he might survive, she has lost most of her interest in him. She would still kill him if she got another chance, but wouldn't bother with it too much. Although Yuna didn't know what exactly was going on, considering how incompetent he seemed to be when his "Madara act" slipped, there clearly is a bigger fish behind him. At first, she thought that Zetsu was the one that was manipulating Obito, but he didn't seem to be much of a thinker either and seemed to get flustered incredibly easily, so Yuna discarded the thought of him being the mastermind as well.
After shrugging her shoulders at her own thoughts, like she no longer cared about this matter, Yuna finished her mental countdown from ten to zero and teleported to the other battlefield. Although she felt quite a bit of pressure on her body and mind after using her technique, fighting the Sanbi should still be somewhat manageable.
Obito, meanwhile, managed to somewhat survive Yuna's attack. There were gashes all over his body, while his arms were barely connected to his shoulders.
Although Obito was close to fainting from blood loss and exhaustion, his Sharingan was practically radiating hatred, and if it wasn't already at the highest level, it would have evolved to it now.