It is my understanding that during Tokugawa era Japan, Samurai could and would occasionally engage in duels to the death. But how often? Do we know from any record keeping how common deadly duels were? How does the number of duels fought relate to how many Samurai there were, how large or small was the risk that a given Samurai would have to fight a duel over his lifetime? Were there noticeable ebbs in the number of duels throughout the period?
Wikipedia is surprisingly sparse on the matter. I believe noble families in Japan used to keep records of family members; if these also mentioned cause of death, one could get a pretty good estimate of actual numbers. I'm more interested in "typical" Samurai, not in exceptional figures like Miyamoto Musashi.
ETA: This answer indicates that private duels where outlawed and punishable by death by many Daimyo even before the Edo period, though enforcement was not 100%.