You run every day and soon you become a human that can go beyond the normal speed limits of man. You run and you run and you run. This training allows you to become super human. You go beyond the limits of a normal human. You become a human who can run really fast.
To solidify your ability to go beyond the abilities of other humans, you etch (えつ) sacred runes into your legs to preserve your running abilities. Etching these runes makes sure that your skills will never deteriorate.