There aren't any records of people using chakra before that, no, not even myths. Although there's barely any records, period.

Apparently not. And that's the only account that concludes with anyone going to the moon. The story seems to consider that there's only the one moon. 

The only other story with someone being born in a plant that she can find is a brief reference to the tale of Momotaro, whose parents found him in a large peach. 

There isn't much here, but there isn't much in the way of recent records in this particular library anyways.

Are there indications where the Sage learned, in that case?

Momotaro?

Well, that seems to be about the limit of what she can get from these records on this area of things. (She notes to look into the moon.)

How about the more modern ones? Geography? Recent social structures? Important groups of various sorts?

Nope.

The legend of Momotaro describes how an elderly couple, who wished desperately for a child but never had one, found a small boy in a giant peach. He grew up to be a hero of legendary strength.

There's almost nothing on geography, social structures, or governments beyond the continent she's currently on. There's maps available of this continent, and books on its governance, though.

Geography, social structures, governments, and maps of the continent she is currently on are of high interest.

The geography is strange, biomes suddenly ending and beginning, and usually in illogical places, if these maps are to be believed. There are mountain ranges here and there, mostly to the north and down the center of the continent, but also lone valleys and mountains where they probably don't belong. 

Social structure seems to have been in flux recently, with a rigid, almost casted structure beginning to break down. Usually violently. The provinces were governed by warlords, or by daimyo, who often may as well be warlords nowadays in the opinion of this one author, and the daimyo generally appointed his eldest son as his successor. Except this one recent case, where a daughter gained the position after her brothers and father mysteriously died, and a few other similar cases. The main distinction between warlords and daimyo seems to be that warlords are only recently risen, are much more likely to be female, and don't use the samurai families for their armies, often relying on shinobi, rogue samurai, peasant forces, and assorted mercenaries. ('Peasant forces' seems to mean anyone fighting that the author doesn't think should be fighting, rather than a reflection on quality.)

She might find this more strange if it weren't for her own world of origin. (Hers doesn't have quite this, but it has enough physical features that would not happen sans magic that she does not find this world's traits particularly a shock.)

Does 'mysteriously' mean about what she'd assume?

How do the shinobi fit into this casted structure? What makes a samurai rogue? Who do authors generally think should not be fighting? Is anything in particular leading to the breakdown? How far back does the structure date? What does it being almost-casted look like?

(She notes the warlords. If she at some point finds it would be most advantageous to pursue such a position, what can she currently learn that might be relevant to either the decision or the undertaking?)

Possibly.

The shinobi were part of the people considered outside and below the castes, including entertainers (which may or may not be a euphemism), the Ainu, convicted criminals, and unclean professions. There also used to be people above the castes, like the shogun and the emperor and their families, but that stopped with the fall of the empire. 

Rogue samurai seem to be mostly mercenaries, rather than working for a daimyo as part of a samurai family. Authors seem to think farmers, artisans, merchants, and basically anyone who isn't part of the samurai class should not be fighting. 

The main cause of the breakdown seems to be the general instability following the fall of the empire, and the rise of shinobi and warlords destabilizing the military structure, and the shinobi and warlords not caring about castes. It's unclear how far back the informal structure dates, though it was only formally encoded a few centuries ago.

Not everyone fell into a caste, and the merchant, artisan, and farmer castes were semi-fluid.

Warlords mostly seem to have arisen as a result of farmer or merchant rebellions, though there's been a few rogue samurai and shinobi who've established themselves. They vary tremendously in their politics - some are harsh to their people, some are permissive, and the permissive ones seem to be more popular. There's at least one woman who graduated from highwayman to warlord, and seems to be something of a folk hero. It seems like hiring low-level shinobi and mercenary forces in enough numbers to overwhelm the daimyo's few samurai is relatively cheap.

She sees.

Ainu? Unclean professions? Is being a convicted criminal hereditary?

What exactly is the shogun, as opposed to the emperor?

What specifically were the castes? Would they be identifiable somehow? (Can she cross-connect to any features of locals she has seen?) Who else did not fall into a caste?

What tends to cause rebellions? 

How is popularity expressed? What traits make this one in particular a hero?

She will note this to keep in mind.

The Ainu are apparently a group of people, but their characteristics are unclear beyond 'these few authors don't like them much.' Unclean professions seem to be things like 'executioner' or 'butcher'. Being a criminal is not hereditary, though the families of criminals are looked down on.

The shogun was a military leader several centuries ago. The position slowly took power away from the emperor; two centuries ago, the position of shogun stopped existing. 

The castes seem to have been 'samurai,' then 'farmers,' then 'artisans,' then 'merchants.' They don't seem to be very identifiable other than if you know their profession. Rich cloth like silk and gold thread used to be restricted to the emperor, his family, and the daimyo, but not since the empire's fall, though some daimyo still tried to enforce similar rules. There isn't an indexed list of all the castes and who goes where anywhere, unfortunately.

'Lack of consistent food' and 'too high taxes' seem to be the most common causes of rebellions.

Popular warlords have more cooperative and happy peoples, who are more likely to rise to their defense if someone else tries to take over. The folk-hero mostly seems to have been such because she mostly robbed the wealthy, was known to be courteous to the poor, and had several adventures of note, including a high-profile romance, and when she became a warlord she promoted all of her advisers from among the workers and farmers. 

Emperor and daimyo and such were also samurai caste?

Reading, noting.

They are/were considered 'above' the castes. 

Mm.

Other aspects of the social structure? These clans she hears about? (The 'catalog of clans, their publicly known techniques, and their symbols' book?)

There unfortunately isn't a guide to the locals laid out, just what can be pieced together from internal writings. Among shinobi, clan heads are usually assumed to either rule uncontested, or have to balance with the clan elders - it's unclear if in some clans this is a formal rule or tradition. Clan heads are usually male, as are fighters. There's some descriptions of the Uchiha clan; they're considered odd for employing female soldiers. The Uzumaki clan are considered odd for front-lining women and using seals in combat. 

The catalog of clans is sparse, mostly focused on the Land of Fire and its immediate neighbors, and is from the perspective of the Senju - it lists the Aburame (a noble clan, reclusive, use chakra-draining insects, not much else is known), the Uchiha (another noble clan, violent and spiteful, use fire and swords heavily, crow and cat summons have been observed), the Hyuuga (the third listed noble clan, can see through solid stone and behind themselves), the Inuzuka (outspoken, usually accompanied by nin-dogs), the Ino-Shika-Cho alliance (the Akimichi, Yamanaka, and Nara - who apparently focus on physical might, mind techniques, and shadow manipulation), the Chinoike clan (powerful genjutsu, suspected to have been wiped out by the Uchiha), the Hagoromo (sometimes allies of the Uchiha), the Fuuma (aggressive, known for using a four-bladed giant shuriken in battle), and Hatake (known for lightning techniques) are among the more notable clans listed. Most simply have names and last known location, with little mentioned about their techniques. 

Rian had said they had nobles, samurai, shinobi, and civilians - she would assume farmers, artisans, and merchants are the civilians, and the nobles are - their own caste? Above the castes?

She'd also said the clans were the fighters and nobility - so the nobles and the samurai would have clans, but the shinobi do so as well?

Nobles seem to be considered above the castes, shinobi below them; the noble shinobi clans are an odd exception - they're elevated above the rest of the shinobi in most authors' eyes, possibly being related to samurai clans, and are considered more honorable in their dealings.

Reading, noting.

And, she has remaining questions (about some of those power descriptions, for instance), but she's been doing this for some time, at this point - is it getting close to dinner? (she has awareness out to notice things like that.)

Yes, rather close.

She will head for the cafeteria; given lack of familiarity, a desire to gain it, and a desire to observe people further, arriving earlier is useful.

She isn't the first one there - a few people have already gathered to eat - but she's one of the earliest, and there's plenty of seats available.

She'll take a seat, not immediately next to anyone but not isolated, and look around.

She doesn't recognize anyone there except as people passed in the halls; a few of them are now identifiable as part of a specific clan - there's two Yamanaka over there, talking to a Nara, and a Hyuuga sits in one corner, glaring at her food. An Inuzuka is slipping food scraps to a dog the size of a pony. Many of the clans seem to have not been documented in what she found earlier, though.

As she has met less than ten people, she is not surprised to not see acquaintances. She notes the clan memberships, known as well as unknown. Any other traits she might fit meaning to, with her newly acquired knowledge?

That man and woman over there, dressed in ornate armor, are likely samurai who used to belong to an official clan, given their apparent wealth. There's another woman who likely has a bloodline - her skin is a light green, patterned with darker green tracery, and her eyes are gold. That person - unclear if male, female, or other from dress and appearance alone - has snake-patterned summoning tattoos on their bare arms. Another person has small storage seals on his wrists. A small group over there, with dark skin and hair in a variety of shades ranging from 'white' to 'dark brown' (and one 'blue') appear to be from Lightning Country.

Hh-hm.

Any indications of how the meal process proceeds here?

People seem to be getting food from a buffet-style wall, then bringing it back to their tables. There isn't any indication of payment needed for food, but most people are only taking a modest amount. The utensils are likely different than she's used to, but some quick observation shows how to hold and use them.