Ryoumin Classes

So, proper education in the Heian period was likely limited to people in the Ryoumin classes.

Of those classes, the Imperial (皇族, kouzoku) and Noble (官人, kanjin) classes definitely got full educations with schools and tutors and in subjects we would recognize today.

Koumin (公民, which were mostly farmer peasants) would not need any significant formal education. Any formal records the Koumin would have needed to keep (such as calendars, inventories, tax records, etc.) would have been taken care of by a lower status member of the Kanjin class who would've been assigned to oversee their farm lands.

Although the Shinabe (品部, "court professional") and Zakko (雑戸, "military professional") classes were considered lower status than the Koumin, they likely would have had a basic education in reading, writing and arithmetic. This is because they had fairly regular interactions with the Kanjin class and it would have been good for them to have some level of formal education. They were also what we would call merchants & artisans, which means they would've been running small family businesses and being literate enough to keep their own records would just be practical.

Senmin Classes

Once you get to the Senmin classes, limited or as needed education would probably have been the most common.

The Ryouko (陵戸, servants of the Kouzoku or guards of imperial tombs), Kanko (官戸, servants of government ministries), and Kenin (家人, retainers or vassals of kanjin families) classes would have lived lives focused on service to others and the families/ ministries they served would've made final decisions regarding the direction of their lives. However, they did have the privilege of being able to marry and have children and they could not be bought & sold at will.

If the Ryouko, Kanko, or Kenin were given an education, it would likely have been at the discretion of the families/ ministries they served. I'm certain all 3 classes would have been taught the specific responsibilities and manners required for their service roles, but anything past a basic education would have been highly unlikely. Especially if they worked at very high levels of the government, an inability (or limited ability) to read would have helped maintain discretion and prevent others from using them as sources of sensitive information.

The last two classes, Kunuhi (公奴婢, government-owned slave) and Shinuhi (私奴婢, privately-owned slave), would have been very unlikely to receive even a basic education. They can be bought & sold at will and were not allowed to marry or have children of their own. These slaves are often used as manual laborers and would not have needed to be literate to do their jobs. They would have always had an overseer of some sort telling them what to do.

If a Kunuhi or Shinuhi were to have even a basic education, it's likely a former owner made an effort to give them one. Whether this basic education made the Kunuhi/ Shinuhi more or less valuable on the slave market depends entirely on cultural norms as well as what sorts of tasks their potential owners would want them involved with.

Zuijin/ Zuishin (随身)

A Zuijin/ Zuishin is someone who is a bodyguard of an Imperial (皇族, kouzoku) or high-ranking Noble (官人, kanjin) official. According to the Japanese Wikipedia page on the subject, anyone with this rank was considered a "ryogenokan" (令外官), or government official whose rank is not specified in the administrative code of the ritsuryō, or social hierarchy. In other words, they literally exist outside the class system. The reason for this is because Zuijin/ Zuishin are very high-ranking people (官人, kanjin) behaving like very low-ranking people (家人, kenin).

You see, the Zuijin/ Zuishin of the early Heian period (794-858 CE) were all members of a government office of the Imperial Court known as Konoefu (近衛府). To be members of this office, they needed to be nobles (官人, kanjin) of no less than 5th rank, which means they had full access to the Imperial Palace. So, the earliest Zuijin/ Zuishin were aristocrats (官人, kanjin) guarding other aristocrats (官人, kanjin) or royals (皇族, kouzoku). As the Japanese Wikipedia page says, "due to the nature of their duties, [the Zuijin/ Zuishin] had close personal relationships with the lords they were responsible for guarding, and these relationships tended to turn into personal, lord-vassal [a.k.a. kenin (家人) style] relationships." This was especially true during the Fujiwara Regency period of government (858-1068 CE), as the Zuijin/ Zuishin realized that the Emperors were merely figureheads and would have been keen on showing loyalty to the Fujiwara families in order to maintain their own high-status positions.

Thank you for your patience! As far as I've read, farmers (also referred to in academic literature as peasants or cultivators) were originally members of the koumin class, i.e. citizens or freemen.

I say originally because most of the farmlands that farmers worked on were public lands that they paid rent/ taxes to the government to cultivate. It used to be the primary way the Heian government collected taxes from its populace. However, there existed a system of private land ownership, called the shoen (荘園) system, where the once public lands (by imperial charter) became tax-exempt. Aristocrats & religious officials sought to cultivate wealth and power by claiming large portions of public land as part of their respective shoens and using the would-be tax money as funds for their personal ambitions.

Eventually, so few public lands were left to cultivate, farmers were forced to work the fields of shoen. This was problematic in that, over time, many of the shoen owners and managers found legal loopholes to trap the farmers in the shoen, turning them into a kind of slave class known as "shoumin" (荘民). Now, shoumin isn't an official caste in the social hierarchy, so those farmers weren't literally slaves, even if they functioned as such.

However, shoumin did have a few vestiges of their original koumin status preserved.

Firstly, every owner/ manager had to have a legal contract (a.k.a. shiki) on file for every farmer on the shoen to prove that the farmer had agreed to (or sold) their right to cultivate the land to them. If such a contract couldn't be found, the farmer had a much greater chance of leaving a shoen he'd been previously bound to. If the shoumin were slaves, who can be bought & sold at will, such a formal contract wouldn't have been necessary.

Secondly, the shoumin farmers were prohibited from selling their children during times of crisis. You see, famines were tragically common throughout the Heian period and many farmer families attempted to sell their children to save them (and possibly themselves) from starvation. However, selling a person is something done to the lower senmin classes, not the upper ryoumin classes, of which these farmers technically were. So, by imperial decree, the shoumin couldn't sell their children because of their "high" social status.

Lastly, only citizens (i.e. koumin) were required to pay taxes/ tributes for working someone else's lands. On public lands, these payments would go to the government. On private lands (i.e. shoen), these payments went to the owners. So, the shoen owners/ managers used a feature of their original koumin status as the rationale for why they taxed these poor people into poverty.

Heian Period Social Hierarchy (Ritsuryo) - Male Court Rankings

(The chart is easiest to read from left to right.)

During the Heian period, Japanese society was divided into two broad social classes: the lower classes (senmin) and upper classes (ryoumin). Within the senmin class, there are five sub-classes. 

The highest of the lower classes, the ryouko, are dedicated servant families to the Imperial family, often as the guards of Imperial tombs. They would be serving individuals with the rank of Emperor, Crown Prince, and Prince. Underneath are the kanko, who were families dedicated to running the public ministries too menial for the ryoumin. Beneath them were the kenin, who were often the servants of high-ranking families beneath the Imperial family, who would be of the First to Ninth Ranks. Under them are the kunuhi, families whose members were hereditary slaves to the Imperial Court or the Public Ministries. Lastly, the shinuhi are families whose members were hereditary slaves to families of the ryoumin classes.

The majority of what is known about the Heian period is known about the ryoumin, or upper, classes. The lowest of the upper classes, the zakko, are miscellaneous houses of nobles or former nobles. The shinabe were the craftsmen and artisans. Koumin were the average free citizens of the realm. Kanjin are the government officials who possess one of the nine Heian court ranks. Lastly, at the top of the pyramid, is the kouzoku, which is the proper name for Emperor and his extended family and concubines.

The chart begins to expand with the kanjin class. Broadly speaking, the majority of these class members can be classified as kuge, or aristocrats. However, they are generally divided into 3 classes of kuge. Kuge who possess court ranks nine (a.k.a. initial rank) to six are called jige, or menial aristocrats. In the eyes of most kuge, the jige aren’t considered actual members of the nobility. The offices to which members of the jige ranks are assigned are largely empty, ceremonial positions with little to no real impact on the happenings within the Imperial Court. 

Courtiers holding the fifth and fourth ranks are called tsuki, or lesser aristocrats. Among the kuge, they are considered true nobles, but of houses of lesser importance. These courtiers are known as those with “court access” because they regularly appear at all major court events. Their ranks are also tasked with real jobs that have regular impact within the Imperial Court. The kizoku, or true aristocrats, are the highest ranking nobles under the Imperial family and exclusively possess court ranks from three to one. These ranks populate the highest levels of the government bureaucracy and these families are often minor branch families of the Imperial family line.

Heian Period Social Hierarchy (Ritsuryo) - Male Court Rankings

Firstly, I apologize for the poor image quality

Secondly, these Court Ranks and Titles only apply to men. Women, by and large, either inherited their court rank from her father or, if it was higher than her own, from her husband through marriage. This is because women did not actively participate at court in a capacity similar to that of men since the reforms made by Emperor Saga (reigned from 809-823 CE).

The colors under the “Court Ranks & Positions” column are applicable during the years 710-724 CE (SOURCE)

The following websites were used to reference the traditional Japanese colors used during the Heian period (SOURCE) as well as the RGB/CMYK designations of each color (SOURCE)