Japan's elite during the Heian period were the creators and consumers of high culture. The peasants did not partake of any poem parties. Nor did they write any pillowbooks. They lived their lives within their own class culture, and most had no contact at all with anyone from the court, except indirectly, through court appointed local officials.
The samurai are a different story. At the lowest level, a samurai might be no better off than most peasants. These samurai might not own very much. A little land with a few peasants working it, providing him just enough income to maintain a few horses and his weapons and armor. Of course, he would have a family name, something most peasants would have to wait until the 19th century for. But with a family name come family aspirations. Not winning is okay, but for god's sake, don't do anything that might imperil the existence of the family name. For the highest ranking samurai were stresses were the same but the stakes larger, for they were literally the sons of emperors.
Every monarchy faces the same simple problem--ensuring an heir. The king or queen must have at least one child survive to adulthood, preferably one who is mentally fit to rule. Queens are in a bit of a bind since they have to actually produce the child. Lots of stress and effort for a maximum payoff of (roughly) one child per year. Kings have it better. Assuming no pesky religous issues about the number of wives or concubines a monarch is allowed, a king is limited only by physical constitution and the number of women he can find. Five or ten potential heirs a year is quite possible.
So you have a baby-booming king trying to literally be the `father of his country'. Problem: You only need one heir and maybe a backup heir for insurance. Court intrigue being what it is, having too many people with royal blood running around can be almost as bad (from the monarch's point of view) as having too few. So what do you do with the rest of the king's / queen's kids after you have decided on an heir?
In Nara and Heian Japan, it was common to send young men with royal blood off to the hinterlands, where they could set up a new