He decided to target Hinata Hyuuga only as the last resort, if everything else fails. He doesn't want to mess with the original plot too much. Stealing eyes from the Hyuuga heiress would be a very bad idea.
Elders from the main branch are out of the question too. They're basically living in the Hyuuga compound 24 hours a day under the watchful eyes of the tens of Byakugans, the same as Hinata's little sister Hanabi.
Hinata was originally his first option because she goes to the ninja academy every day and it's possible for him to somehow succeed in stealing her eyes on the road. But he didn't calculate the political implications this would bring. Every Konoha ninja including himself would probably be researched, and maybe his whole cover would be blown away.
Stealing the eyes of a side branch Hyuuga who is incorporated into Konoha's shinobi forces would be a different story. He will start from there and see if he could take their eyes without them blowing up from the curse mark.
Ao from the Kirigakure in the original series managed to clearly steal one Byakugan eye on the battlefield. He doubts that the scarce main branch members would go to the battlefield, so it must've been a side branch member he took it from.
He suspects that as long he steals those eyes while they're still alive, it would work.
Official Konoha ninja with Byakugan would be very easy to find, as long as he asks around a little bit. ANBU members were a different story of course. He will also look for any injured or retired Hyuuga members in the village who lived outside the Hyuuga compound right now.
He immediately tasked his teammates with finding out about this. One would go looking for active Hyuuga ninja in Konoha's forces. While the other would go and look for injured or retired Hyuuga ex-ninja living in the Konoha.
He already had the tools necessary for the extraction. As well as the plan to dispose of the bodies.
While waiting for the news from his teammates. He started thinking about other things. He thought about the possibility of obtaining the Tenseigan after the surgery so he was very excited.
He also realized that with his personality Might Guy will never give him the Eight-gates technique.
So either he has to blackmail him into somehow giving it to him. Or just straight up steal the written scroll of this Jutsu from his house.
He will also slowly try to befriend Sasuke Uchiha and trick him for his promise with Orochimaru.
He guesses Orochimaru is the closest person to him in this new life. Orochimaru is the person, most similar to him in this world. So he doesn't want to kill him.
Orochimaru's goal was obtaining the true immortality and his own goal is being the strongest he could and fighting and defeating the strongest enemies.
He even wants for Orochimaru to succeed and obtain the immortal body through the Sharingan vessel. He doesn't even mind giving him some advice later on.
Kabuto as well. He was very polite to him all the time he was there with him. He knows that he had a very tragic life before, so it's justified that he turned out to be the way he is now.
Even though they conspired to take over his body. He doesn't hold anything against them for that. He even respects their motto of doing everything and anything for achieving their final goal. That is his life motto as well. They're kindred spirits he guesses.
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Kimimaro was currently sitting at the table and looked at the people before him. They were called Yoroi Akadō and Misumi Tsurugi. They're his current teammates as well as the other two spies that Orochimaru installed here in the Konoha.
They're very arrogant and brash in nature. They also tried to start something with him, when he first took Kabuto's place. But after he showed them his favorite bone drill, they calmed down and turned to respect him a little.
He smiled and said: "So what have you found in these three days?"
Yoroi the ninja with dark glasses replied: "We've found seven Byakugan holders in the current Konoha's shinobi forces. No retired or injured members were found. Out of those seven, four were currently on a mission"
Kimimaro said: "Impressive. What are the ranks of those three people not on a mission currently?"
He remembered the face of one guy who's now on a mission. He was the one he stole the Hyuuga DNK from.
"All are Chunins in Konoha's ranks. Here's the file of all the information we've found about them" Yoroi replied and gave him a file.
There was usual stuff there. Like where they lived, where they liked to go out, their hobbies, times they were at home, etc.
He was very happy now and said: "Thanks for the help guys. You're free now"
After they left, he smiled darkly and left as well. Night time is now, and they were all at home, waiting for him.
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He was wearing a black camouflage now and moved very fast in the darkness. He decided on the unlucky guy who will be his first try.
Other two guys lived near each other, so it would be a problem if the other guy sees him in the middle of the surgery.
But this guy lived all alone without any family members and at a relatively remote corner of Konoha that is. Perfect for him.
He soon came there and jumped on the roof of his house. He then drilled a hole with his bone and jumped in. The guy probably sensed something and woke up, but it was already too late.
Kimimaro got him in a trap with his flexible bones. One of his new skills he developed after he cured himself of his old illness.
The guy said: "What's happe..." He didn't manage to finish as Kimimaro stuffed a piece of bone in his mouth.
"Sorry man but who told you to buy a house in this remote corner of the village" Kimimaro said and took out his surgical knife. He didn't waste any time and started extracting his Byakugan immediately.
The guy had his eyes ripped out while he was still alive so he cried and twitched a lot. Every cut was unimaginable painful and Kimimaro had to do it slowly to not damage these precious eyes.
Soon he took them out completely. 'The hard part comes now' he thought.
As a person from the Earth, ripping his eyes out and replacing them with new ones was pretty unimaginable to him. 'The pain must be very bad' he thought again.
But for his goal, he had to do it. He was also used to pain, living with that crazy illness for years where every part of his body hurt every day, every hour. Not to mention the torturing taijutsu training he took under Orochimaru.
He decided to do it quickly. He prepared his bone tentacles already. He will use some of them for extraction. Then he will use the other ones for putting his new eyes in quickly.
He did it! But he was very quick to do it too, so he only felt a very sharp pain for a split second. After waiting for a while, he walked to the mirror in this guy's room.
In an otherwise dark room, the two little light flicks were clearly visible in the mirror. That was Tenseigan! He started laughing aloud, he couldn't contain it anymore. He can't even imagine how powerful he was right now.
He laughed for five minutes straight, then realized the guy was still alive on the ground deadly scared from his laughing. 'He would probably cry now too, if he had his eyes that is.' He looked at the poor guy and moved closer.
He looked at him and said: "Thank you man, you can't even imagine how happy I'm right now.
The heights that these two eyes you gave me will bring me is simply unimaginable. I'm very thankful to you for that, and I will remember you for the rest of my life.
Don't be too sad tho. There'll probably be some kind of afterlife for you. I mean everything is better than going on missions every day, eating, drinking and then coming back to sleep in this poor apartment every day alone.
Come on now, you didn't even have a girlfriend, man. I pray to Heavens that you find yourself a nice girlfriend in your next life. Maybe even a wife. Goodbye now, bro. You'll be remembered."
Then he drew back every tentacle he had already dispatched.
Then he pulled a different bone from his sleeves. But, this one was in the grey color. He threw it at him and waited. Soon, his body started dissolving into ashes on a molecular level.
'Amazing' he thought. This bone could kill almost anyone. This bone was the famous All-Killing Ash Bone of Kaguya Otsutsuki.
His Shikotsumyaku was originally only a part of Kaguya's Kekkei Mōra, All-Killing Ash Bones.
Of course, It's to be expected from him to unlock the full version of this ability once he changed his genes to be 50% Ōtsutsuki/Kaguya's.
Soon his whole body dissolved into ashes. He took out a small body bag from his pocket and stuffed his remainings there. "I'll pour it all into the sewer later." He thought.
He moved home very fast. 'I need to hide this Tenseigan fast!' he thought.
But once he got home, he just collapsed on the floor and his Tenseigan disappeared. He tried to activate it again but he didn't have enough chakra left.
"So this isn't a complete Tenseigan yet? Do I need more chakra in order to support it?" he thought.
Either way, it was better this way. He now had normal grey colored Hyuuga eyes. Which he will mask with the contact lenses he made a while ago even before coming to Konoha.
He needs to lay low a couple of days. Even though it's only a side branch member, the whole village will be on the alert for the next couple of weeks, for sure.
He left some traces. Like the hole in the roof. But there is no way to connect that to him. And that was the most efficient way to enter.
"Poor guy...' he thought again, now realizing that he didn't even remember his name...