The Jorōgumo clan is both a driven group, as well as collectively vain. The members of the Jorōgumo clan find value in that which lies on the surface, that they might optimize the use of their clan's hijutsu. This results in an outwardly confusing internal society, and makes the true machinations within the clan quite confounding from the eyes of an outsider.
"Appearances are Everything." Everything. To a Jorogumo, what lies beneath the surface means nothing. Well, almost nothing. If you believably become another person, what does it matter that you are not truly them? To outsiders, traditionally raised Jorogumo are obtuse to the point of ridiculousness. How you present, how you dress, how you talk- the Jorogumo can be incredibly judgemental, though they often do not voice disapproval. But the look in their eyes is less friendly and more calculating.
While their perception as "cold, unfeeling, calculating" is not unwarranted, the Jorogumo are obsessed with learning, specifically learning about people and what makes them who they are on the surface. Their clan arts rely upon it, in fact. Just because they look like a person does not make them believable.
Amongst themselves, the Jorogumo are labyrinthine in their social norms, and close friends often have minutes of inside jokes and codes to suss out whether they are talking to the person they believe they are. The art of performance and impersonation is in their blood, and it's often a fun practical joke to dress up as someone else and see how far you can go before someone calls your bluff.
The clan used to have a large and needlessly complicated hierarchy, with various branches based on whether they were civilians or ninja, performers or assassins, but the many ninja wars have driven the clan into pieces. Pockets of the Jorogumo still exist, but they have largely abandoned the artifice that failed them over the passage of time. At the very most, the Jorogumo act as a very large extended family, and that comparison is often literal. Unrelated Jorogumo tend to be in distant villages to each other, with very little cohesion between them.
Jorogumo was never a last name, or even a title the clan ever gave themselves. It was more of something that was thrown upon them by others, in an attempt to classify them in order to better understand them. Long before ninja villages were a thing, there were performers. Artists, actors, seamstresses and makeup artists, plying their trade for whoever would give them food and coin. In these days, people were only just starting to learn how to harness chakra. A bunch of common performers had no such need for such things.
Until, of course, it was used against them. They were not warriors, and bandits knew this. The Jorogumo learned first how to hide, then how to fight. And even then, they were not good at it. Broken sticks and feeble threats were nowhere near enough to defend them, so they learned how to evade.
It wasn't until the world calmed down that the nascent clan was able to settle down and become something more. The first Ninja War began, and it sent many of the Jorogumo running for the hills, desperately looking for a place to hide, to wait for things to blow over. In Getsugakure they settled, though the village existed only as it was for a moment, much like a dream. The Second Ninja war struck, and the performers had only just begun to find a role in warfare. They were subpar ninja, but excellent spies. They kept their new land safe primarily through sabotage, well placed lies, and the occasional morale-improving performance.
By that point, the Jorogumo had gained their name. Sinister spiders who loved to entice enemy ninja to their doom. It was during this era that a few members of the clan had discovered a talent for something macabre: stealing faces. It was an accident at first, pushing too much chakra into someone they were trying to kill and simply lifting the face from their dead flesh. It wasn't until the war grew dire that the Jorogumo began to wear them.
They kept this a well-guarded secret from others. They didn't want their newly gained reputation as killers and deceivers to follow them. But, word getting out was inevitable, and the village under the Moon became too uncomfortable for them to remain in.
Wandering once more did not do the clan many favors. They had begun experimenting with this new face-stealing abilities, and developed a new, less murderous jutsu. It was much easier to use, though it had many more drawbacks. Requiring the use of a mask, the Jorogumo found that they could easily infiltrate the ranks of other militaries, provided they could study a target and then become them.
When the third war hit, the Jorogumo were shattered. Already losing most of their cohesion once they abandoned Getsugakure, the Thrid war ended with the members scattered to the winds, everyone jumping ship to become mercenaries and eventually settling across the world. Having ended up in a position to continue being ninja instead of civilians, the newly scattered Jorogumo fought for where they decided they would stay. By the time thirteen grueling, painful years of war had ended, all cohesion among the clan had been lost. Not to mention a good chunk of their population.
But as a whole, they were stronger, better trained, better focused. Now, small pockets of the face-stealing clan live and thrive in the various ninja villages, living their lives without truly knowing where the rest of them are, besides the ones around them.
Originally descended from theater troupes and costume designers, the Jorogomo as a clan prize appearance and deception in all things. A traditionally raised member will have learned the arts of mundane disguise and acting from early on. However, acting does not a shinobi make. The Jorogomo plied their trade as ninja specifically because they discovered a grisly tactic: Stealing Faces. Both metaphorically and literally. Divided into two hidden techniques, the Jorogomo use Chakra to become other people they study long enough in the metaphorical sense, and assassinate targets and assume their identities by literally robbing them of their faces.
Face Copying Technique
Kao Utsushi no Jutsu
Requiring the use of a blank mask (which any Jorogomo worth their salt has in spades), Kao Utsushi is a flawless transformation. After studying a target for a period of time (the time ranges from a solid week for Genin, to about a day for Jonin) a Jorogomo can enchant a mask to appear to become their target. Since the technique requires a lot of setup, the Jorogomo will have mastered their target's body language and mannerisms, and their voice and scent are literally perfect, not even trained Ninken can tell the difference.
The Downsides are many. First of all, the Jorogomo does not become their target in any way. They merely look like them. They do not gain access to any of their target's memories or abilities, and without careful planning can blow their cover quite easily. Equally regrettable is that the process that turns the mask into a focus for this transformation makes it incredibly brittle. A well place taijutsu or bukijutsu attack to the face will shatter the mask instantly, breaking the disguise and undoing the Jorogomo's hard work.
Vanishing Facial Copy Technique
Shōshagan no Jutsu
The Jorogomo hide this high level (B Rank) technique from even their most trusted friends if they can manage it. Requiring that their target is completely unresistant (i.e. dead), the Jorogomo lays their hand over their face and then lightly pulls, literally stealing the face of their unfortunate victim. The subsequent corpse's features are completely wiped away, leaving nothing but blank, smooth skin.
If the Jorogomo then wears the face, the technique activates, changing their skin and voice to be completely identical to the original owner of the face. Unlike the previous technique, Vanishing Face does not break immediately upon contact, though with roughly three Bukijutsu or Taijutsu blows the face will tear, dispelling the illusion. Like all Jorogomo techniques, this jutsu does not grant the ninja access to any of their target's memories or abilities.