To create a workable plan, Fujin had one clone in the library the entire time that he wasn't on missions. His clone looked through the entire library to find any methods and seals to help him find a way to infiltrate the Uchiha compound.
After researching and practicing for a month, Fujin had found all the means to create a plan and try his luck while ensuring his safety and anonymity. He began the preparations.
While Fujin was making his preparations, the Uchiha clan too began their preparations. All active Uchiha ninjas were called back. Every single Uchiha ninja returned back to Konoha. They began to prepare themselves for the war.
Meanwhile, Danzo met Itachi in secret and explained to him what would happen when the Uchiha revolted, once again. He convinced Itachi to take action against his own clan.
However, while the two were talking, their actions were seen by one person. In his room, Hiruzen watched their whole interaction in his crystal ball. Surprisingly, neither Danzo nor Itachi sensed anything off.
Tiredness could be seen on Hiruzen's face as he sighed on seeing his friend's actions, 'I would have stopped him. Unfortunately, the relationship between the village and the Uchiha clan has deteriorated beyond repair.'
His expression became firm as he decided not to interfere, 'While it's true that they were relocated to the outskirts of the village and monitored by Anbu, no Uchiha was ever mistreated by us. I can understand that they would be dissatisfied with such a treatment. However, this is no excuse for launching a coup that would destroy the village.'
On deciding the fate of the Uchiha, Hiruzen's eyes fell on Danzo, 'My old friend, it looks like you have completely fallen into Darkness. This will be the last time you will interfere in the matters of my village.'
While the undercurrents were flowing in Konoha, Fujin was busy in his basement making a lot of complicated seals. A day after Mieko told him the news, Fujin completed the first step of his plan.
He took a deep breath, 'Finally, it's done!'
He made a hand sign. A shadow clone appeared next to him. The clone made multiple hand signs. Fujin observed the clone by concentrating chakra in his eyes. He could see that the chakra signature of the clone was slowly changing. Soon, it was very different from Fujin's chakra signature. His scent also changed.
Fujin thought, 'Good, now it will be difficult to link the clone to me.'
After the clone completed the process, Fujin applied another scent to the clone to make it look like he was hiding his real scent. Next, the clone used the Transformation jutsu to transform into a Honey badger. Fujin thought, 'Normally, seeing this animal in the streets of Konoha would raise suspicions. But, the Uchiha clan compound is on the outskirts of Konoha. If it appears there, it won't cause any suspicion. After all, there are many of these in the forests inside Konoha. '
After the clone transformed, Fujin began making seals on its body. He first applied seals that would increase its affinity to Earth nature manipulation. This way, it would have an easier time moving underground and would also reduce any chances of it being related to Fujin as Fujin wasn't known for his Earth element.
He followed it up by applying numerous stealth seals on the body of his transformed clone. Soon, the honey badger couldn't be seen, heard, smelled or sensed! Fujin checked his work several times until he was satisfied.
Finally, he nodded and said, "You'll be responsible for the first task."
The honey badger didn't reply. Fujin made a hand sign and sealed him in a special storage scroll.
He created a wind clone who took the storage scroll with him and flickered multiple times in the forests next to his house. After coming to a very secluded place far away from his house, the wind clone opened the scroll and let the honey badger clone out. The honey badger clone checked his surroundings and moved stealthily towards the Uchiha clan. He moved under the ground so as to not leave any trails.
The wind clone also left. After going away sufficient distance, he destroyed the storage scroll and dispersed himself.
The honey badger quickly moved towards the Uchiha clan compound but did not enter it. He had no intention of testing his seals against the Sharingan. Instead, he went to the route that Uchiha kids would take while going to and coming from the Academy and stayed there.
The honey badger clone thought, 'The first task consists of two missions. The first is to keep an eye on Uchiha Sasuke. The day Sasuke returns very late from the academy will most likely be the day the massacre happens. And, the second task is to see if anyone notices me. If someone does, I will drop all plans of stealing that dead body.'
While this clone kept an eye, Fujin created 5 more honey badger clones. They would roam through the forests and training grounds in Konoha to see if anyone notices anything suspicious in them.
Fujin had calculated, 'Honey badgers are rather common in Konoha. So a few more of them shouldn't raise any eyebrows. However, if someone is still able to somehow figure out that they are my clones, I can just admit that they were made by me and I was practicing stealth for missions. After all, I haven't done anything wrong yet. If no one notices anything strange, then I'll deploy them around the Uchiha clan.'
The honey badger clones would roam around Konoha all night and disperse themselves when the Sun rose. Fujin experimented for two days before deciding that they were safe to be used. From the 3rd day, all 6 of his honey badger clones used to stay around the Uchiha clan compound. In addition, Fujin would maintain 2 wind clones at one secluded spot a few kilometers from the Uchiha clan compound.
With the preparations done, Fujin just waited for the right moment.
A few days later, in an underground base under Konoha, Danzo stood with a subordinate. The subordinate respectfully asked, "What job do you have for me, Danzo-sama?"
Danzo looked at him and said, "Your Triatominae bugs can induce sluggishness, right?"
The Root ninja was from the Aburame clan. He replied, "Yes Danzo-sama. They can cause slight sluggishness with their poison. And since it poses no direct threat and doesn't have any color or smell, it is almost impossible to detect."
Danzo said, "Good. Your mission is to poison the drinking water that reaches the Uchiha clan with this poison. Use very small quantities. Your main priority is that this poison isn't noticed. Once you are done, go to training ground 49 and wait for me."
The Root ninja was surprised by the mission. However, it wasn't his place to question Danzo. He nodded and left. Danzo watched him leave as he thought, 'He was a good subordinate. A shame that he has to die.'
Danzo called another subordinate of his and instructed him to approach the Aburame ninja in the training ground 49 and kill him and dispose of his body as well. Though Danzo's subordinates had his curse seal, no seal was perfect. Considering the importance and severity of this matter, Danzo decided to take this step. This way no one other than him and the elders would know about the truth of the Uchiha massacre.
The Root ninja from the Aburame clan did his job exceptionally well. Since it only caused a slight sluggishness, no Uchiha ninja realized that they had been drugged. After all, they didn't have to move at full speed in their normal lives.
Danzo made a few more moves that day. He ensured that no Hyuga, Inuzuka or Sensor ninja was in the vicinity of the Uchiha clan compound to prevent any interference. In fact, he had ensured that most of their active ninjas were on duty outside Konoha.
Finally, on that evening, Uchiha Itachi and Uchiha Obito appeared in the Uchiha clan compound. Almost everyone in the village was oblivious to the massacre that was about to unfold. Only 3 were aware of it and waited patiently.
Danzo was busy with his Root ninjas to ensure that Itachi wasn't interrupted. Meanwhile, he also had to ensure that his Root ninjas weren't close to the Uchiha clan compound and get caught in the fighting. Hiruzen had recalled all Anbu ninjas that were keeping an eye on the Uchiha clan. While Fujin was waiting in his basement for his clones to send him a message.