Grandmaster (martial arts) of "Dan" rankings and Black belt and Red belt in martial arts both derive from Judo where they were adopted by its founder Kanō Jigorō. There are many terms similar or equivalent to 'grandmaster' used by various martial arts traditions. Some of these terms derive from older systems, while others are relatively modern. Japanese martial arts commonly use Sensei (先生) meaning "teacher" or literally translated, "born first" or "one who has gone before". A "Sensei" is a person who has knowledge and is willing to teach that knowledge to another. A "Sensei" assists students in "ken shiki" "the pursuit of
Japanese martial arts rule of thumb, the primary purpose of a "koryū" martial art was for use in war. The most extreme example of a "koryū" school is one that preserves its traditional, and often ancient, martial practices even in the absence of continuing wars in which to test them. Other "koryū" schools may have made modifications to their practices that reflect the passage of time (which may or may not have resulted in the loss of ""koryū"" status in the eyes of its peers). This is as opposed to "modern" martial arts, whose primary focus is generally upon the self-improvement (mental, physical,