Madara accepted the mission scroll Tajima gave him, skimming over the contents until he nodded his understanding. Tajima may be a shite excuse for a father, but he was a splendid shinobi with a discerning eye, knowing exactly what sort of missions Madara could excel with his physical age in consideration.
Unlike his first childhood, Madara was by far too skilled to be kept out of missions and battles despite only being physically five-years-old. Furthermore, with how sombre and ruthless he was, taking lives left to right without an ounce of hesitation - his 'first' kill had been swift and unsympathetic - he knew his clansmen whispered about him being a disturbing child.
It stung, but he has always been good at compartmentalization. If he could not inspire love, he would cause fear.
He coped by ignoring every judgemental whispers until it all became background noises, their words unintelligible to his ears. Even now, he doubted that his parents noticed his selective mutism and withdrawn behavior; his father's only concern was to build him into a perfect war general-slash-leader in their battles against the other clans whilst his mother diligently continued to reproduce replacements if Madara were to ever be KIA.
Frankly, he had forgotten how people felt about gender in this time period. Especially for those who were born into a clan that prides in bloodline limits. There were no women in their army, for fear of others capturing them and using them to breed.
To the people born and bred in this era laden by countless clan wars, women were little more than child-birthing machines unless they were insanely strong. Children were little more than cannon fodder or a purpose to strengthen their numbers. Clanless ninjas roaming the place with no other than reason than to kill for food on their table.
Madara loathed the Warring States Period. It was nothing but aimless pandemonium, and as a man who had once fought against the entire shinobi world, he only did so with a purpose in mind; for peace, as misguided as it was.
Madara tucked the mission scroll into his drawstring pouch and waited silently until the man dismissed him, looking directly into his father's dark, narrowed eyes and having no fear of the man's Sharingan prowess. Genjutsu was an ability gained from one's superior will, unbending mind, and precise chakra control. His physical body played no factor as he could easily counter any man-made illusions thrown his way. The only issue he has was with his stamina and small reserves.
Although he was trusted to complete missions that only children twice his physical age were given, proving to Tajima that he was a prodigy, the man looked as if he was contemplating something. Tajima ended up saying nothing after five minutes ticked by.
As soon as he was sent out of the man's study, he grabbed his oversized (to a child) mission bag, kissed Izuna on the forehead, and left the compound immediately.
After gaining a fair distance, he set his bag down and retrieved a senbon and a pigmented ink pot. Having sterilized his senbon with a small fire jutsu, Madara, with meticulous care, inked a seal - white in color - on his right tricep. It took him many months to smuggle the materials to handmake his own ink, but it was worth it.
In this period, only the Uzumaki were masters in fuuinjutsu - and even then, tattooed seals were never thought of before Tobirama came about creating the ANBU tattoo. Jinchuuriki seals were a different branch altogether, and Mito was the one who invented it and became the first ever Jinchuuriki (technically, since nobody knew Ĺtsutsuki Hagoromo was the Juubi's Jinchuuriki).
Hence, if he were to unluckily enough to be caught, no one would suspect a child from the Uchiha clan to know anything about seals, much less use it in such a risky way.
Seals tattooed on the skin, if inked incorrectly or made by someone without a mastery in the art - as the people decades later had come to learn after trying to imitate Tobirama's ANBU tattoo design blindly without understanding its concept - could result in a painful death as their chakra would rebel; similar to how white blood cells fight an infection.
(Madara had been so bored, his elderly life spent in a dark cave, siphoning chakra from the Gedo Statue, with no company other than the White Zetsu clones. He had ordered them to sneakily bring him fuuinjutsu scrolls from the Uzumaki over the decades he was alive so that he would be able to understand the sealing arts better. As for why he mastered them; he was a perfectionist, always will be. When Uzushiogakure fell, he had Zetsu salvage what they could, before moving onto other hobbies when he had read all that he could read.)
After he was done, making sure that the items stored inside could only be released once specific conditions were met, he sealed his mission bag, leaving only his makeshift shuriken holster strapped around his left thigh and an adult-sized sheathed katana slung across his back.
All in all, he looked like a child who stole their father's weapon and ran away from home. Not that Madara cared. If others underestimated him, it was their own funeral.
Patting down his navy blue mantle sans Uchiwa fan on the back, he continued on his journey and entered Senju territory. His mission wasn't in any way related to the Senju. However, he would be able to complete it quicker if he cut through their territory to reach his destination.
Madara loathes having Izuna out of his sight for prolong periods of time. And with Ryouta due to be born soon, Madara desires to not miss his second younger brother's birth.
With the help of his chakra sensing abilities - although his range was in no way comparable to Tobirama's - he artfully avoided the Senju patrols for the whole day and camped high in the trees, hiding inside hollowed trunks during the night to avoid detection.
It took Madara a total of two weeks to reach the small fishing hamlet belonging to the Hagoromo clan, what with his pitiful stamina and short limbs.
His mission was to blend in and investigate if the Hagoromo clan were 'worthy' enough to be allied with. Madara already knew that their clans had once been allies against the Senju back in his first life, but if possible, he would rather they not ally themselves with such scum.
He recalled - thanks to his perfect memory - that that clan made a sport of hunting children from opposition clans ("My little brother was killed. Madara, right? Have you any younger siblings...?"). To nip the bud before they could grow. It was distasteful to Madara, who had once upon a time dreamed of building a sanctuary for his younger brothers, for children to grow naturally rather than be forced to mature and die prematurely.
And yes, he knew he was being hypocritical.
He had manipulated many children in his old age - and Obito was his biggest mistake as of yet. Madara knew that if he ever lived long enough to meet Obito once more, he would train the boy properly this time. Not as a stooge, but as a direct disciple. He owed the other Uchiha for all he has done to the young lad. How unforgiving he had been to tear all that young Obito loved and made him grow into such a twisted man.
(... Obito, that endearing brat, had made the loneliness he accumulated throughout the decades dissipate, gradually, ever so slightly, but he had been too stubborn in his quest for peace to cherish those moments. He had been such an old fool, too obtuse to realize that he had already adopted Obito into his family and yet, still used the younger Uchiha like a disposable tool. He regrets. Oh, how he regrets and feels such shame...)
Madara couldn't help but stare at his pudgy hands, currently free of blood but heavy with stolen lives and burden. Despite this body's young age, his body count was plenty, enough to put even some adults to shame. He truly was someone who brings nothing but pain and misery onto others.
He physically shook himself out of his self-hatred and changed his clothing to blend in better with the homeless orphans and street rats.
The mission lasted a total of three months if he counted his travel time.
Whilst his father stoically read Madara's mission report back in the clan head's office, he sat outside his birthing mother's bedchamber with Izuna tucked under his chin, the two brothers eager to meet the latest addition to their family.
What he didn't write in the report was that in the process of observing the Hagoromo clan, Madara had accidentally pushed and prodded a few holes in their meager defenses which then allowed their enemies to spit on them whilst they were down. Oops. Well, they have nobody to blame but themselves. Thus, proving that they were not worthy to ally themselves with the Uchiha.
Despite having no urge to retry his Eye of the Moon plan, Madara has always been a master puppeteer, stringing those along without their knowledge and making others dance to his tune - he worked best in the shadows than the light, after all.