Earth sometimes referred to in the series as The Old World was the original home of the human race. In the Dirty Pair series, the human race left this planet in the past and established civilization in space throughout multiple planets. The country known as Japan was the where Yuri's descendants were from. A tradition from Earth mentioned in the series was the holiday known as Halloween which was being celebrated in the anime OVA "Count Us Out! Ultimate Halloween Party". In the Dirty Pair Flash series, a planet known as World's World was created to replicate the lifestyle of Earth in the late 20th century.