Three years passed in the blink of an eye.
Izuna has been regularly doing missions in Anbu. He has become the Captain of Team Ro because of his contributions. During this time, he will sometimes train with Itachi and Shisui.
Itachi has graduated from the academy and recently became a Genin. Orochimaru had escaped the village when Hiruzen found out about his experiments. Kakashi was able to get over his grief from the death of all his team members thanks to Izuna and Sakumo. Sakumo personally trained Kakashi and Kakashi grew a lot stronger.
Initially, Kakashi faced a lot of problems with the management of Chakra. Izuna solved the problem of the Chakra drain caused by Sharingan. He created a Fuinjutsu seal to deactivate Kakashi's Sharingan. Kakashi had to form a Ram seal to activate the Sharingan.
Kakashi still adopted his usual style of covering his left eye with the headband.
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Izuna lies on the training ground while monitoring the progress of Shisui and Itachi. Both of them have grown stronger than their Original counterpart thanks to Izuna's training.
Izuna will secretly train Shisui in the construction of Susanoo. Shisui quickly grasped the technique and improve at a rapid rate. Now, he can make an upper Body Humanoid Susanoo.
'I have successfully mastered many other Kekkai Genkai nature Transformations. I have to figure out a way to learn Sage Mode. If I can learn the 'Six Paths Sage Mode' then I can easily heal Minato and Kushina.
The 'Sin Seal' has stopped bothering me. The Yin half of Nine-tails provides ample amounts of Chakra for the seal to suck dry. In my current state, I can easily defeat Grandpa Madara with his Eternal Mangekyo Sharingan. As for Rinnegan… let's not talk about that.
I am currently the strongest shinobi of the Shinobi World, excluding the Otsutsukis and that unknown cloaked person.'
A shiver ran down Izuna's spine when he thought about that fight.
'Who was he? He is aware of this 'Sin Seal' and its's powers. I refuse to believe I killed him with that attack.
I don't know the extent of his powers. But if I have to make a guess, then he is at least as strong as Momoshiki Otsutsuki. I wonder what happened to him after my attack.'
Izuna shakes his head and quietly stares at the interactions of Shisui and Itachi. A young Sasuke walks up to him and lies beside him.
"Izuna Nii-san, teach me a jutsu. Father won't teach me any jutsu, and Itachi Nii-san is busy training with Shisui Nii-san. Only you can teach me a jutsu now." Sasuke stares at Izuna with his puppy eyes as he puffs up his cheeks.
Izuna pokes Sasuke's cheeks and reply,
"Sasuke, you are only four this year, why do you want to learn ninjutsu this quickly?"
"Nii-san, I want Father to praise me just like Itachi nii-san. So, Nii-san, please teach me a jutsu." Sasuke stares at Izuna with puppy eyes.
'Aw… so, cute. I can't say no to such a cute expression.'
Izuna pulls Sasuke's cheeks.
"Ok! I will teach you 'Fire Style: Great Fireball Jutsu'. You can later impress Uncle Fugaku with the jutsu. Now, follow me to the Nearby lake. I will show you the hand signs for the jutsu. Memorize them and practice slowly."
Izuna walks to the Uchiha lake and slowly makes the hand signs for the technique.
'Fire Style: Great Fireball Technique'
He spews out a large fireball above the lake. Lots of lake water evaporates from the jutsu.
"Now, it's your turn."
Sasuke haphazardly makes the hand signs and spew out a small orb of fire that flickers for a while before extinguishing. Sasuke drops his head depressingly.
Izuna rubs Sasuke's forehead.
"Don't be sad, Sasuke. You did well for your first attempt. If you practice diligently, you will eventually reach the same level as me."
Izuna cheers up Sasuke.
"Come, I will treat you to your favorite popsicle."
"Yay! You are the best Nii-san." Sasuke hugs Izuna.
Izuna and Sasuke walk through new Uchiha compounds while licking a popsicle. Izuna receives a signal from a nearby hidden Anbu member. He stops in his footsteps and urges Sasuke to continue,
"Sasuke! Big-Brother has some urgent work to handle. Go and play with your friends. Also, don't be mean to Naruto. Don't allow others to bully him. He is also my younger brother, just like you.
So, that makes you an elder brother to him. Protect your younger brother from bullies."
Sasuke puffs his cheeks in annoyance.
"Nii-san, why I have to take care of that baka Naruto?"
Izuna gently strokes Sasuke's head.
"He is the son of my late teacher. So, it is my responsibility to take care of him. If you take care of Naruto and protect him from bullies, I will teach you many cool new jutsus." Izuna tries to entice Sasuke.
"If you say so, I will play with Naruto and protect him from other bullies." Sasuke nods his head.
"You can also call him during your training, I will teach both of you. Now, big-brother has to go." Izuna vanishes from the spot in a burst of particles.
"Wow! So cool. I want to learn this jutsu." Sasuke looks with shining eyes.
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Inside the Hokage's office,
Izuna appears in front of Hiruzen in his Anbu costume.
"You summoned me Hokage-sama." Izuna bows in front of Hiruzen and waits for his orders.
"It has been four years since you joined the Anbu. From a normal member to a Captain, you have risen in ranks quickly. I have received your request for retirement from Anbu.
I would like to know the reason behind the request. Your career as a shinobi is at its peak, and Anbu lacks geniuses like you. It would be a waste to let go of such talent from Anbu." Hiruzen stares at Izuna.
Izuna removes his Anbu mask and replies to Hiruzen,
"I had my fair share of bloody battles and missions throughout my career as an Anbu. I am tired of all this bloodshed and I would like to explore the world outside Konoha. So, after my retirement, I will journey across the 'Shinobi World'."
'Also, I have hit a plateau in my growth recently. I have mastered and honed my skills in these three years. I am not a rookie with a lack of experience anymore.
I have to figure out a way to master Senjutsu or Sage Mode. I will start with Shikkotsu Forest. Then there is a lack of proper summoning creatures for me. I haven't been able to form a proper contract yet. The 'Sin Seal' won't allow me to form a contract.'
Hiruzen contemplates for a while before he replies,
"I will process your request as soon as possible. But before you retire from Anbu, I have a Last mission for you as an Anbu Captain."
"Please, Hokage-sama! I will complete the mission." Izuna nods to Hiruzen.
"Humm… Amegakure has been suffering from a civil war since the Third Shinobi War. Hanzo's rule in Ame lead to many bloody slaughters and large-scale genocides.
Recently, a new organization called Akatsuki has appeared. You are aware of the fact that Orochimaru escaped from the village this year. I have my suspicion of him joining this organization."
Hiruzen picks up a file from the table and passes it to Izuna. Izuna skims through the file while listening to details from Hiruzen.
"We don't have any detailed information on this organization. But from our sources, we have tracked the origin of this organization to Amegakure. Our previous attempts to gather any intelligence failed miserably. All of our previous spies are MIA or murdered in cold blood."
Hiruzen passes another list with the name of spies and their duration of mission in Amegakure. Hiruzen continues.
"Danzo previously lead his Root team to investigate the matter. But I had lost trust in him after his recent attempt to assassinate me. He has grown quite power hungry in all these years. But I can't remove him, his Root is too crucial for the survival of Village."
Hiruzen sighs and reminisces about his past.
'Sensei! I have failed the last mission you gave me. Danzo became the darkness of the Village, but he is slowly getting consumed by this Darkness.
I can't bring myself to kill my disciple and now my lifelong friend. I am too soft-hearted.'
Hiruzen takes a deep breath and continues.
"I have issued this top-secret mission to you. It will be an infiltration mission. Infiltrate the Amegakure and gather intelligence on the current situation of Ame.
Also, remember. If the situation turns too dangerous to continue the mission, immediately abandon the mission and retreat to Konoha.
You are the third person to master the 'Flying Thunder God Jutsu', your life is far more valuable than any intel. It won't be an issue for you to escape from enemies' encirclement. Now dismiss."
Hiruzen dismisses Izuna. Izuna disappears from the spot in a burst of particles.
"I still can't get used to this kid's technique."
Hiruzen slumps down on Hokage's chair and smokes from his pipe.
'Orochimaru! I hope I haven't made a mistake to allow you to live.'
Hiruzen contemplates while smoking from his pipe. He pulls out the drawer and picks up a large Crystal sphere.
"It's time to watch the progress of Konoha's new seedlings."