As a child from a Ninjutsu family and a transmigator who had read Hokage, Uchiha Mukaku naturally understood the Summoning Technique contract scroll.
The Summoning Technique is a space-time Ninjutsu used by a user to summon a Summoning Beast after forming a blood contract with it. However, this technique has other uses. The user can use space-time Ninjutsu to store various items in the contract scroll and then summon them out for use with the Summoning Technique when needed.
Anything that can be sealed can be handled this way, such as Ninja tools, corpses, and puppets. If an effective connection can be established, even the souls of the dead can be summoned, and Edo Tensei is an example.
Furthermore, this Ninjutsu also has a very powerful reverse operation called Reverse Summoning Technique. While the usual Summoning Technique involves the user expending his Chakra to summon a contracted animal, the Reverse Summoning Technique involves a contracted animal summoning a person, which is a rather advanced Ninjutsu.
However, the conditions for this operation are extremely strict. First, the contracted animal must possess sufficient Chakra; second, the contracted animal must have the ability to form hand seals; third, the contracted animal must have sufficient intelligence.
The Summoning Technique contract held by Uchiha Yukio was a scroll, on which the terms of the contract between the user and the Summoning Beast were recorded. The user must write his name on the contract and press a blood handprint to finalize the contract.
Uchiha Mukaku, without even asking what kind of Summoning Beast contract his father had obtained, decisively pressed his bloody handprint and wrote his name on the contract. After all, when it comes to Summoning Beasts, the more, the better; no one would complain about having too many.
After completing these steps, Uchiha Yukio gently stroked his son's head and then took the Summoning Technique contract away.
The Summoning Technique contract is an extremely important item; if this contract is damaged, the user will no longer be able to summon the corresponding animal on the contract, so it must be properly preserved.
After his father left, Uchiha Mukaku, feeling playful, immediately used the Summoning Technique, wanting to see what his Summoning Beast looked like.
He cut his finger, quickly formed the hand seals: Boar-Dog-Rooster-Monkey-Ram, and pressed his palm to the ground. A puff of white smoke appeared before Uchiha Mukaku.
When the smoke cleared, a medium-sized Ninja Cat appeared before him. It was about twice the size of a regular house cat. Its fur was smooth and soft, with a gray and black pattern, the black fur forming irregular patches on the gray base, like dark clouds obscuring the sky. Its face was long and narrow, and its eyes were amber, but one of its eyes had three distinct claw marks, one above and two below.
This Ninja Cat was wearing an outfit similar to that of a Japanese ronin. The clothes were dark gray, with some wear and patches, indicating a somewhat down-and-out life. A red belt was tied around its waist, from which hung a small Ninja sword. The scabbard had several scratches, suggesting it had been around for some time.
As soon as this Ninja Cat was summoned, it looked up and saw a child of about five years old in front of him. In an instant, it became spirited, straightened its back, and spoke with arrogance in its tone: “Brat, did you summon Myatsuro-sama?”
Uchiha Mukaku couldn't help but frown. He absolutely could not tolerate a Summoning Beast riding over him. In his heart, he had to make this ignorant fellow understand what proper hierarchy was, otherwise, this guy would not only fail to be an asset in battle but would become a burden.
Thus, Uchiha Mukaku unhesitatingly threw a powerful punch at the Ninja Cat. The Ninja Cat flew out like a kite with a broken string, “whoosh,” and crashed heavily against the wall with a dull thud.
This hit left Myatsuro a bit dazed. Although it had just acted extremely arrogant, it had actually been secretly observing the other party's reaction. One must know that a cat's reaction speed is three times that of a human. It usually prided itself on its speed, but it never expected to completely fail to dodge this child's attack this time.
Before Myatsuro could recover from the sudden shock, he saw Uchiha Mukaku pull out a cold, gleaming, incredibly sharp kunai. At this, Myatsuro immediately put away its roguish demeanor, lowered its head, stopped wagging its tail, and respectfully prostrated itself on the ground, saying in a fawning tone: “Myatsuro greets Uchiha-sama!”
Seeing the other party's fawning appearance, Uchiha Mukaku contentedly put away his kunai, then grabbed a handful of coins from his wallet and threw them in front of the other party before speaking: “I am Uchiha Mukaku. From now on, I am your master. Take this money to buy snacks!”
“Hai, I will obey your command!” Myatsuro did not immediately move but responded with great respect in his tone.
Uchiha Mukaku smiled contentedly, then asked, “What abilities do you have?”
“I know a bit of swordsmanship and some simple Ninjutsu. My specialty is gathering intelligence and tracking,” Myatsuro answered honestly.
“What Ninjutsu?”
“Three Body Technique!”
Uchiha Mukaku couldn't help but be a little surprised. He didn't expect this Ninja Cat to be so powerful, capable of using the Three Body Technique. If this were in peacetime, it would be enough to qualify as a Genin.
However, this guy offered no enhancement to his combat abilities, so Uchiha Mukaku lost interest in Myatsuro. He turned and walked out of the room, saying without looking back:
“I already know. You may leave on your own!”
Myatsuro lay on the ground, motionless, just quietly lying there until Uchiha Mukaku, this “plague god,” had completely left. Only then did it joyfully gather the coins in front of him and put them into its bosom, then directly turned into a puff of smoke and vanished without a trace.
...
Uchiha Mukaku came to the courtyard and took out an aluminum plate from the storage room. This was his practice tool. To train his Chakra control ability, he was cultivating the C-rank Ninjutsu, Finger Carving Seal.
This technique involves concentrating Chakra into the fingertips to generate a certain amount of heat, then carving text onto the target. It can be carved on both living skin and iron plates, but it requires very high Chakra control.
Jiraiya once used the Finger Carving Seal in his dying moments to record Pain's secret on Fukasaku-sama's back.