As the Democratic Party of Japan's presidential election nears, an interesting fact has surfaced regarding internal regulations on who gets to vote for the ruling party's leader — and effectively the prime minister.

The Sept. 14 election, the DPJ's first major presidential race since 2002, will be open not only to Diet lawmakers but also to regional assembly members and the estimated 350,000 registered party members across the nation.

With kingpin Ichiro Ozawa throwing his hat in the ring Thursday to face off against Prime Minister Naoto Kan, it will be the most heated presidential race in the party's history.