Priestly ranks run from the guji, the chief priest of a shrine, through negi and gonnegi. Certification comes from a four-year degree at Kokugakuin University in Tokyo or Kogakkan University in Ise, or from shorter courses run by prefectural shrine offices, and there is a system of ranks and licence grades administered by Jinja Honcho. In practice succession is heavily hereditary: a substantial majority of priests are sons of priests, and shrines are commonly held by a family across generations, which is a genuine problem when a generation declines the job. Women were admitted to the priesthood after the war — an emergency measure when male priests died or were away, subsequently made permanent — and now make up roughly a tenth of the priesthood, with a handful of chief priests of major shrines. The miko, the young women in white and vermilion who assist at rites, sell charms and dance kagura, are usually students on part-time contracts, and are required by most shrines to be unmarried; the role descends from something considerably older and stranger, the female spirit medium of the archaic period.