Planet Ymir is a world in the Tau Ceti star system, known primarily for its luxurious casinos. Yusof Munsi is a merchant ambassador for this planet.
Ymir is a fairly barren world, although it does contain a number of artificial gardens.
Gambling and tourism are the two major industries of the Tau Ceti system. However, the early settlers were afflicted by depression and alcoholism, so the natives rarely partake in gambling themselves. The planet is home to a number of criminal cartels.
Being pacifists, the people of Ymir also remained largely neutral during the two Galactic Wars. They aren't particularly interested in politics outside of their own star system.
Gail Pilgrim abandoned Jojo here after he got distracted by drinking and gambling. Diane Romero was brought up on this planet by her father Carlos Romero.