Kaguya calmly walked in the direction of Zetsu in an even and measured, regal gait as if she was taking a stroll through the forest, completely unbothered from the fighting that was going on nearby.
One stray attack could kill her. She was aware of that. But it was not like being killed would mean she would die. Her body was just a clone with her consciousness imbued in it, after all.
Frankly, if she died, she would at least have an excuse to return to her cookies.
'On the other hand, Rei would most likely just summon me again to finish my job. Haa~, the sacrifices I make for that silly man.' Kaguya shook her head with a small happy smile stretching on her lips, not even realizing she was almost skipping.
He really wouldn't summon her back if she died since this was but a misunderstanding but she didn't need to know that...
She finally arrived at her destination and could clearly feel Zetsu being hidden in the ground a few tens of feet under her. This was only possible because Zetsu was technically still a part of her. For others, even S-rank ninjas like Sasori or Kakuzu, he was practically invisible with his concealment technique.
'Now... how to announce my presence.' Kaguya wondered, lamenting her current lack of chakra and the limitations of her clone body.
If she was in her true body, she would just Bansho Ten'in him to the surface, probably half-killing him in the process. 'Sigh. I really miss my convenient universal solution.'
Alas, while she definitely had the ability to manifest Rinnegan even in her current body as it was more spiritual in nature for her than physical, her chakra was not enough to activate it in her current body.
And that was only manifesting it. Actually using it for something... now that was utterly impossible. Her body would go out in a poof if she even started to try.
'Rei could at least give me enough chakra for the task.' She inwardly grumbled, deciding to make her displeasure clear when she returned.
Poor Rei really didn't expect her to just up and go enact this harebrained wish of his and when she did so, he was first too stunned to stop her before he became curious how it would turn out.
Attempting to convert Zetsu was honestly a stupid move at the moment. So much could go wrong with that it was not even funny.
Rei had no idea if the guy would think Kaguya was an impostor or if he would recognize her through her chakra or something. One thing was certain, however. Simply looking like Kaguya would not be enough to persuade Zetsu. The henge was a Jutsu taught in the academy for a reason, after all. And with Kaguya in her weakened state...
For all the plant-guy knew, his 'mother' was still sealed in the moon and he was given the grand quest of getting her out. Having her casually pop up in front of him... there was no telling how he would react.
Either he will have a way to ascertain it is really her or... he won't. And if he doesn't have such a method, then a shitstorm will follow.
Zetsu would get to know that somebody out there knows about his mother and he would no doubt be on a quest to exterminate them with extreme prejudice. Not that he actually could do much directly. The problem was his indirect involvement. The guy was centuries old and participated in controlling even people like Madara from the shadows. He might not be capable of hurting Rei or his girls but he was good enough to make things difficult for Rei's and his girls' villages or companies in some roundabout way.
Obito targeting Rei's companies was harmless. The guy was a mostly straightforward type. His scheming ability only went as far as Zetsu allowed. All brawn and very little brains. If he had brains, with his Mangekyou Ability, he could have won the war or forcefully gather all jinchuuriki very easily.
Zetsu was a different kind of animal altogether. He thrived in darkness and loved manipulation. A dangerous combination for a ninja world.
Yet, Rei was too curious to stop Kaguya and decided to simply observe this meeting from afar through his sensing abilities.
"Hmm... if I remember right, Zetsu should have unparalleled detection ability." Kaguya mused out loud, cutely putting her index finger on her chin in a pondering manner. "He is probably feeling my presence but ignoring it because of how little chakra I have, deeming me unimportant. That sucks." She clicked her tongue in mild irritation. "It would take a proper deep look at my chakra for him to recognize me. How to get his attention, though..."
Kaguya was a bit disgruntled. For the first time since she met Rei, she felt severely limited in what she could do. Sure, she was also in clone body when in Rei's mansion in his village but she didn't need her abilities there so she never really noticed nor cared how limiting her current state was.
It was frankly frustrating and brought a beginning of depression to her as it reminded her of the time when Hagoromo was sealing her into the Moon.
"Rei better prepare his special cookies for me after this. Reminding me of such unpleasant memories." She huffed and frowned before knitting her eyebrows together as an idea started to slowly form in her mind.
'Since Rinnegan is out, then...' Kaguya thought before smugly activating her Byakugan and focusing her intent stare at Zetsu to the point even a total amateur at detection would find it extremely annoying to the point of inability to ignore it.
She was basically broadcasting a 'here I am, look at me!' vibe through her gaze. It was the first thing Hyuuga clansmen learned not to do after they activated their Byakugan since ninjas are usually very sensitive to being observed by others.
Zetsu naturally instantly noticed and his head whipped in Kaguya's direction and his eyes landed on hers that were narrowed and portrayed a great deal of impatience. It took only a moment for Zetsu to register her appearance and his eyes widened in shock. He instantly scrambled to present himself to her, not even a shred of doubt about her identity remained in his mind. He was simply too happy to doubt the sight in front of him.
Resurfacing from the ground, Zetsu kneeled, "Mother!" He eagerly exclaimed, getting the feel for her chakra and understanding that yes, the person in front of him was real. "You are here! How is that possible?" He added in disbelief and awe in his tone, confusion clear on his face.
An indulgent and amused smile appeared on Kaguya's face at his antics and apparent loyalty. Reaching out, she subconsciously but gently ruffled his hair. Funnily enough, of all her 'children', Zetsu was the one she felt closest to. He did spend his entire life trying to free her, after all. If nothing else, she was at least grateful for that dedication.
"I am not really free, Zetsu. Not yet." She said and Zetsu's expression instantly fell. Kaguya almost cooed at that. It was as if she just told a child there will be no ice cream after lunch.
"But..." He weakly tried to protest.
"I just acquired a very reliable man willing to help me." She continued and the smile on her face involuntarily widened, "He made this," She gestured at herself, "possible. Only my consciousness can leave the seal for now but I have full trust that the day I get freed is not far off."
Zetsu eagerly nodded, "How can I help?"
He didn't think to question Kaguya or the identity of her helper. To be honest, it didn't matter to him how or why. He was created to get her out of the seal and now that she was at least partially out, it brought him immense joy and hope.
Rei who observed from afar was utterly baffled at how... naive Zetsu seemed. He expected many things but this... not in the slightest.
"Mhm." Kaguya distractedly nodded, "I will need you to continue doing whatever you are doing." She relocated her hand that was nuzzling his hair onto his forehead, earning herself a small pout from him that made her giggle before she used her chakra to imprint what she wanted from him into his mind.
Zetsu's eyes gained a newfound determination as he understood what his mother wanted him to do and that the Eye of the Moon plan was no longer necessary for her unsealing. In fact, he was surprised that she wanted him to subtly steer Akatsuki astray.
A normal human would feel at least a twinge of reluctance after putting so much effort into it. From manipulating Madara to manipulating Obito, to forming Akatsuki, to subtly manipulating Pain, to leading them towards the Eye of the Moon plan... It took Zetsu at the very least a century of continuous effort. Yet, there was nothing but joy and willingness to serve in his mind. He felt no hesitation to make all that effort completely obsolete and meaningless.
It was a clear testament that Zetsu was in fact no human and despite his humanoid appearance, he didn't feel the way humans did.
"I understand, mother. Your will will be done." Zetsu said almost reverently.
Kaguya didn't really react to his worshipful tone. She was used to being worshipped. This was nothing new for her. Frankly, the teasing Rei so often subjected her to was more perturbing for her while also making her flustered most of the time.
It was... oddly good feeling, in Kaguya's opinion.
"Make sure to not cause trouble for the Biri-Biri company, the Uzushio Trading Company, Sunagakure, Konohagakure, and Kirigakure in the upcoming months and wait for the signal to enact the plans I just mentally transferred to you." She firmly ordered.
"As you will." Zetsu nodded, staring at her, waiting if she had any more instructions for him.
Kaguya blinked and tilted her head, "Off you go, then."
And Zetsu wordlessly merged with the ground again, disappearing.
She knew he would not betray her. Zetsu was technically a part of her and he was created in such a way that made his most heartfelt wish to merge with her, becoming again a part of her. That could be done only after she got fully out of the seal and it was meant as insurance that he would not stop trying to get her out. He was her will personified and that was not just in a matter of speech but at the time of his creation, her sons just betrayed her and Kaguya didn't have much trust left in her.
While her state at that time also transferred the corruption of Juubi into Zetsu, making him quite a bad boy, Kaguya was not worried because of that. Rei already promised her he would develop a seal that could deal with the corruption in a permanent manner so when he will inevitably merge with her, ceasing to exist, he will not corrupt her.
'Heeh~, I am kinda good at this scheming thing too if I say so myself.' Kaguya happily nodded with satisfaction at the outcome as she turned around, heading back towards Rei, intending to demand her just rewards.