Samurais were fearsome, well-respected warriors and prominent figures in Japan’s history, but according to some tales, they often killed civilians simply because they could. That may lead some people to wonder if that samurai “fact” is actually a fact, an outright lie, or an oversimplification of a more complex issue.
Some samurai killed civilians. Although it was illegal, some samurai killed passersby at night. Some scholars say they did this to test out new weapons. Other samurai only killed civilians if the person in question insulted the samurai’s honor. This second practice was legal under Japanese law.
This article will take a closer look at both of these relatively common practices during Japan’s Edo period. It will also touch on samurai’s treatment of non-samurai, the reasons samurai killed other people, and the methods by which samurai killed other samurai.
Also see Did Samurai Fight Ninjas? to learn more.
How Did Samurai Treat Peasants and Commoners?
During the Edo period, Japan had a very complex hierarchy of classes and social standing.  At the top of the social order was the Emperor. He was followed by the court nobility, the shogun, and the daimyō.
Those were considered the Japanese elite or aristocracy.
The samurai class fell right under those four classes and acted as the bridge between the Japanese aristocracy and the common classes. Peasants came next, followed by artisans and merchants.
Peasants were fairly well-respected among and well-treated by the Japanese higher classes and the samurai because they grew, harvested, and produced most of Japan’s food. Samurai would kill them, however, if the peasants insulted their honor. They were considered lower class.
There is some truth to the tales of samurai indiscriminately murdering people of the lower classes. This practice, known as tsujigiri, was not legal in Japan during the Edo period, but that didn’t stop samurai from doing it.  However, those people weren’t usually peasants.
Instead, they were usually somewhere further down the totem pole – criminals, prostitutes, or other “undesirables” were common targets of samurai looking to bloody their blades.
An oft-cited reference detailing this practice is Mary Midgley’s essay, “Trying Out One’s New Sword.”  In this work, Midgley claims that samurai killed in this way to test out new weapons. This theory has largely been discredited in more scholarly circles.
There were samurai who killed lower-class citizens seemingly without reason, but there’s no evidence to suggest that they did so to test new weapons. Furthermore, samurai who undertook this practice – of which only one is well-documented as a spree killer – were treated as criminals and punished accordingly.
Also see Did Samurai Use Guns? to learn more.
How and Why Did Samurai Kill Other People?
There was, however, another completely legal reason for samurai to kill commoners – a practice known in Japanese as Kiri-sute gomen. The Japanese ruling class legally sanctioned this practice, which was a common reason for samurai killing commoners.
Samurai would kill commoners who insulted their honor (Kiri-sute gomen) by slashing them with their swords. The phrase “Kiri-sute gomen” literally means “authorization to cut and leave” a victim’s body. Killing someone for this reason and in this manner was considered an act of self-defense.
Although today the phrase is “Kiri-sute gomen,” during the Edo period when this actually happened, the act was called “uchi-sute” or “burei-uchi.” All three phrases had slightly different literal meanings, but they described the same thing – killing someone of a lower class who had insulted a samurai’s honor.
Interestingly, some people were exempt from Kiri-sute gomen. For example, samurai couldn’t kill midwives and doctors who gave offense to them in the course of performing their duties, as it was assumed their jobs were so important (and time-sensitive) that they might have to be rude or uncouth to get to where they needed to be and complete their tasks on time.
Furthermore, whenever a samurai killed someone of a lower class who had offended him, that samurai had to justify the killing to his peers. If the killing was deemed inappropriate to the scope of the perceived insult, the samurai would be severely punished.
Also see Did Samurai Have Squires? to learn more.
Did Samurai Kill Shogun?
Samurai didn’t kill shogun; instead, they served or backed up shogun, helping ensure the shogun, or military elite, held their positions of power. They also served the daimyo in the same role. Samurai might kill shogun from rival clans but never from their own.
Samurai and shogun worked hand in hand to ensure the reign of their particular clan. Shogun were the military leaders; samurai were the warriors who enforced the rule of the shogun and daimyo; they were the power that kept rival factions in check.
Did Samurai Kill Other Samurai?
Samurai frequently killed other samurai, but usually not within their own clans. Instead, warring samurai from opposite families fought and killed one another all the time in effort to take control as the ruling class.
Battles between samurai clans started around 1185 and continued for several hundred years until the late 1800s, when the feuding states period of Japan came to an end. 
It’s not impossible that samurai killed other samurai within their own clans, but they were much more likely to save their aggressions for people from rival clans and families.
When samurai fought against one another, they usually did so on horseback, frequently using ranged weapons such as longbows and arrows, spears, shuriken, or even guns. Although samurai art typically depicts samurai with katanas and other blades, these were the least-used of the samurai’s weapons.
Samurai would occasionally fight with blades, especially if they lost their horses and were forced to fight on foot, but for the most part, the swords were primarily ceremonial.
Did Samurai Kill Themselves?
Samurai would kill themselves – an act known as seppuku – rather than be captured alive by a rival clan or enemy. They often did this by slicing through their abdomens and bleeding out, though sometimes they enlisted the help of other warriors and asked them to behead them.
Being captured alive was a great dishonor among the samurai, one they’d rather die than face.
Also see Did Samurai Exist? to learn more.
Samurai would occasionally kill civilians, though killing them for anything other than a disgrace on their honor was illegal and punishable by law.