After all the Uchiha clan was going to be executed within a year ..
He needed to be prepared for that event ..
So he started to search for a already prepared lab , than to build one himself after all where could he find the equipment he needed for the lab ..
That is why he was searching the whole forest ..
As weeks went by graduation exam came ..
The test involved simple shuriken trowing test and academy jutsus..
On the day of exam he went to the academy and waited ..
Finally the teacher came with another teacher carrying ninja headbands..
The teacher started to call the students one by one and as he was called he performed the clone jutsu he was asked to perform as for shuriken trowing test. He performed 6 out of 10 ..
He was given a ninja headband and said to register his photo in the Hokage building
He also came to know he wasn't getting any team as their was shortage of ninjas .only students who performed the best and had great potential were assigned to team with a jonin teacher..
He wasn't sad about not getting a team .
As he could move freely by not being in a team and perform the missions he preferred.
of course they will be low level but he doesn't care ..
He went back to the apartment and again started training and finding a lab ..
Next day he went to the the Hokage building and gave them their photograph for ninja id .
After that he went to get a mission and was given a simple d rank mission to paint a wall .
He assigned a shadow clone to perform the task and went for training..
After a month he found a lab which was hidden very well ..
His clone entered the lab first to check if their is any safety seal or any other thing their.after finding it safe thd clone dispelled and kirito got the memory and entered the lab and saw dust everywhere and some medical equipments and some jars containing some body organs and some small animals..
He performed a some wind style jutsu to remove all the dust and didn't destroy any equipments .after finding the lab he assigned his 10 clones to perform different experiments their on DNA , chakra,and Central Nervous system..
He daily accepted a d rank mission which is completed by clones ..
He also had to find a way to block the hyugas from sensing or seeing the chakra core in his body and only one solution came that is fuinjutsu which he only know basic ..
So he was trying to find a solution about this and the only place he could find the an advanced fuinjutsu was either Hokage building or Kushina Uzumaki home which he didn't know about and he knew if their was any fuinjutsu scrolls their they will either be snatched by third hokage and Danzo ..or they will be secretly stored by an advanced sealing jutsu at a secret place ..
So he could do nothing for now ..
Soon months went by he became 13 years old..
So he started to assign a shadow clone to sasuke and another to Uchiha clan under camouflage techniques ( concealment jutsu).
As more months went by he started to sense change in the atmosphere and the usual anbu members were replaced by root ninjas ..
So he also prepared many body storing scrolls, chemical jars for storing sharingan and root ninja style uniform..
After a month during evening sasuke class was given additional classes today .
His clone dispelled and he knew time has come.so he didn't trained that day and only sentone clone to perform a simple d rank mission.
After that he traveled near Naka river from were he performed the earth style movement technique and skillfully entered the clan grounds and their he made 40 shadow clones who were assigned to collect sharingans and some bodies..
Because of chakra core his chakra level increased 5 times so he could now make at least 100 clones . He again made 50 clones who were each given a storage scrolls to collect all the money and scrolls the high members of Uchiha clan possessed.
After all he couldn't let this golden opportunity go from his hands ..
So his clones moved secretly with camouflage technique and earth style jutsus to collect the sharingans and he only told them to collect 5 bodies of ninjas from Uchiha clan to study their bodies..
He himself went to fugaku's house and concealed himself their.. He silently waited their ignoring the screams ..
Soon after two hours Itachi arrived at his home where he found his parents waiting for him.
Then some emotional drama happened and he killed his parents while he was crying.
Kirito who was seeing this all couldn't help but think was his tears real as he was a person who slaughtered all the people be it child, women or old people ,he didn't even flinch but now he is crying is it real or some drama ..
But suddenly he felt the presence of a similar person.. Sasuke opened the door while calling his parents and was shocked to find his parents dead and the killer his own big loving brother..Soon after some Sasuke 's screaming as Itachi put him under the mangekyu sharingan genjutsu where he repeatedly showed sasuke the scene of him killing his parents...
Soon Itachi left the house and sasuke also left chassing after him .
When they left kirito soon came out of his hiding place and collected the eyes of fugaku and his wife and collected them in chemical jars ..
He also stored their bodies.. and went towards the the room where he had found the money and jutsu scrolls kept by the clan head .He knew the presence of seals here but he didn't really care now that the owner was dead who would stop him .
So he collected all the scrolls and money and performed earth jutsu to move out of the clan grounds..
He went to the Forest of Death where he circled out and went around different areas and repeatedly performed transformation jutsu and also changed his clothes and removed the scent he had covered himself with to be extra careful he also soaked in the lake and then went to the secret lab and stored everything their , where his clones where waiting for him ..
Soon his clones started to dispell and he didn't experience a headache because of his training and they only had memories of 2 hours ..
He then stayed their for the whole night and at morning he came back to his apartment while hearing the commision caused by the news of Uchiha clan massacre .he didn't care about that and he started performing the missions for a month by himself and didn't go to his lab ..
After the commision started to calm down , he waited for another week and then again started to perform missions by his clones .
He made 15 clones and started to organise all the things he had stealed during the massacre.
He found around 370 million ryō
One mangekyu sharingan
Ten three tomeo sharingan
Five two tomeo sharingan
Thirteen one tomeo sharingan
9 bodies of Uchiha clan members including fugaku and his wife
Many elemental scrolls of the jutsus copied along the Uchiha clan history.
Many genjutsu and healing jutsus.
And mostly fuinjutsu scrolls from basic to advanced..