Tsujigiri

Tsujigiri (辻斬り or 辻斬 tsuji-giri, literally 'crossroads killing') is a Japanese term for a practice when a samurai, after receiving a new katana sword or developing a new fighting style or weapon, tests its effectiveness by attacking a human opponent, usually a random defenseless passer-by, in many cases during nighttime. The practitioners themselves are also referred to as tsujigiri.

Originally, this practice took the form of traditional duels between bushi, but as the classical ideals of bushidō were largely forgotten during the Edo period, the mannerisms of tsujigiri became increasingly dishonorable. By the 18th century, it was not uncommon to hear of masterless samurai ambushing unarmed peasants in the dark for simple amusement.

The practice of attacking defenseless people was especially rampant during the early Edo period, which led the Edo government to prohibit it. Offenders would receive the capital punishment.

Philosophical relevance
The practice of tsujigiri has been cited in the philosophical debate over moral relativism, notably by Mary Midgley in her 1989 work Can't We Make Moral Judgements?. It was used as an example of a custom which, despite being considered immoral by many observers with different cultural backgrounds, was at least at one time considered acceptable by those within the culture in which it obtained.