A few moments earlier,
In the underground hideout in Mountains Graveyard,
Tap… tap…
Obito is sitting on a throne near the remains of God Tree as he raps his finger on the armrest.
"Izuna Uchiha! Why?!… Why must you interfere with our every plan? As long as you exist, Akatsuki could never achieve its goal of world peace.
You are preventing the world from achieving true peace."
*BAMM!!*
He slams his fist on the armrest and cracks it.
"Losing your temper over pointless musing won't lead you anywhere."
Whoosh…
Zetsu slowly gets out of the ground and stands in front of Obito.
"Still, Akatsuki had made no progress in these past few years."
Obito stands up from his seat and walks towards the God tree.
"The Eye of the Moon Plan is necessary for the salvation of this world. We must seek some other way to put our plans into action. Anyway…"
Obito turns towards Zetsu.
"Report me about the situation in Konoha! One of the spies of Sasori informed us about the cooperation of Fourth Kazekage with Orochimaru. They planned to launch an all-out attack on Konoha to wipe it out.
How is the situation over there?"
Obito inquires.
"I recorded the entire series of events in my memories."
Zetsu nods his head.
"And?!"
"… As expected, Sunagakure never stood a chance. Current Konoha is way too strong for other hidden nations to take on by themselves.
Even without Izuna Uchiha, Konoha has many other powerful shinobis like Sakumo Hatake, Tsunade Senju, Fugaku Uchiha, Akira Uchiha, Yagami Uchiha, Shisui Uchiha, Itachi Uchiha, Kakashi Hatake, and various other clan members…"
Zetsu lists a few names. He pauses for a while.
"… also Hiruzen Sarutobi the Third Hokage died in this battle."
"I see."
Obito nods his head.
"It won't affect them much, but Konoha lost one of its spiritual pillars. So… how about the battle of Izuna Uchiha?"
"No… I didn't get a glimpse of it."
Zetsu shakes his head.
"There was a barrier erected to prevent outsiders from intruding on the battle, and I didn't venture closer because of the fear of being discovered.
Hmm…
"But he lost an arm in the battle." Zetsu adds.
"That won't affect him in any major way. Re-growing an arm isn't a major deal."
Obito slowly caresses his body.
"I am more concerned about the person who left him in such a state. Izuna Uchiha by himself is enough of a threat to ruin over plans, and now another person with similar strength appears out of nowhere." Obito muses over the matter.
Hmm…
Black Zetsu ponders the details.
'From the memories, I inherited from mother; mother prepared the white Zetsu army to combat a very powerful enemy. Could it be him?'
'NO! It isn't possible. Izuna Uchiha will never stand a chance against Mother, much less the calamity mother was prepping for.'
Zetsu shakes his head.
'More and more variables are appearing in my plan. Till now, I have been manipulating the shinobi world to create the present history; but with the appearance of Izuna Uchiha, everything seems to go out of my control. I have to get rid of him at any cost.'
Black Zetsu stresses his memory for a method to overcome the current predicament.
"Found it! This should work."
An idea clicks in Black Zetsu's mind.
Hmm…
Obito raises his head and turns towards him.
"Zetsu! Do you have a plan?"
"Yes, I do."
Zetsu nods his head.
"You are aware of the fact that I am Madara-sama's will and have inherited all of his memories!"
Mm…
"That's true." Obito nods his head.
"… after his battle with Hashirama Senju; Madara-sama seemingly lost his life, but he defied death through the use of Izanagi…"
Zetsu continues.
Hmm…
"… disgraced by his death, Madara-sama swore to pay the debt to Hashirama Senju. So, Madara-sama wandered the shinobi world to seek greater power.
On his journey, he came across an ancient ruin hidden deep in the Land of Sea hidden away from the mainland."
Whoosh…
Zetsu rolls out a map of the Shinobi World as he marks a certain spot.
"This hidden ancient ruin is filled with many deadly traps and seals, and it is almost impossible to unlock the secret buried in its depth.
Madara-sama could only venture to one-fourth of the ruin before being forced to stop. Still, with only one-fourth of the exploration; he could come across such marvelous weapons and treasures."
Zetsu points towards various weapons and scroll decorated on the walls of the hideout.
He points towards the ring on his hand and remarks.
"These rings were also a part of the treasure of those ruins."
"Zetsu! If even Madara Uchiha failed, then how do you expect me to succeed. It would be pointless suicide if dared to attempt it." Obito scrutinizes Zetsu.
"Back then, Madara-sama was alone and had yet to awaken his Rinnegan. But now with the help from the members of Akatsuki and Pain; I am sure we would be able to dig out the secrets of this ruin."
Zetsu assures Obito.
"Hmm… that's reasonable. If this could give us an edge in our plan; then it is worth the shot." Obito nods his head.
"Very well, I will visit Nagato and make preparations." Obito picks up the map and swirls out of the hideout.
"You make a fine storyteller, Black!"
White Zetsu remarks.
"I told him half the truth."
Black Zetsu scoffs at White Zetsu.
"There are four Otsutsuki ruins spread throughout the corner of the shinobi world. I learned about them from Mother's memories.
After her war with Hagoromo and Hamura; Hagoromo sealed one of the ancient Otsutsuki ruins with a powerful seal. The second ruin became a part of the seal which sealed mother and now it resides on the moon.
The Third ruin was forever lost in that chaos. Even I am not aware of its location.
As for the final ruin, it is located on an unnamed island located in the Land of Sea. These ruins are our sole chance of turning the tides in our favor."
Swoosh…
Zetsu enters the ground.
-----------------
Inside the Hokage Office,
Tsunade is sitting on her Hokage chair as she turns to Izuna.
"Izuna! Are you sure it is a good decision to let two jinchuruki meet each other?"
Tsunade peeks out of the window as Gaara is talking with Naruto.
"Yes! It is the right decision." Izuna nods his head.
"I would have just straight up killed Rasa to give this kid a better future. But I will let things play out like this. Besides, this child will only suffer in Suna. I don't need to remind you about Naruto's childhood."
"Naruto!"
Tsunade clutches her fists as the schemes of Danzo freshen up in her memories.
"If not for us, he too would have become a tool for the village, just like this boy. I am no saint when it comes to these matters, but I am humane enough to consider the feelings of this innocent child.
The people who seek to manipulate such a pitiful child are the real monsters. TSUNADE! Power in itself is neither evil nor good. It is the people who wield them that ultimately decide its nature.
The tailed beasts are sentient beings made of energy. Like us, they too desire to live a peaceful life; but it is the greed of a few power-hungry people who attempt to use them for their nefarious purposes."
Izuna remarks.
'Sorry, Grandpa, I am selling you out on this one. I hope we will be able to reconcile over this.'
Izuna closes his eyes.
"But still! How do you plan to raise him?" Tsunade asks him.
"Well, for the time being, he can live with Naruto. He is a shinobi by birth; so of course, I will train him as a shinobi."
Whoosh…
Izuna raises his hand as a small sand ball form in his hand.
"Besides, I can easily teach these party tricks of Rasa to him."
"You never change, do you?!"
Tsunade shakes her head.
"Well, it won't be me; if I change." Izuna shrugs his shoulders.
'I hope I will never change. The fear of death doesn't faze me; it is the fear of being unable to see my loved ones that shake me to my core.
Death! Huh!… Let's see who will win this race.'
------------------------
A/N:- In canon, Orochimaru had a secret lab in Land of Sea where he first created his cursed seal and branded Anko. I will leave the rest to your imagination.