The MRC argues that the former British protectorate should never have been integrated into Kenya at independence.
He wants independence for Kenya's Indian Ocean coast, a paradise for visitors where locals live in poverty.
Ruwa leads the Mombasa Republican Council (MRC), a secessionist group outlawed by the Kenyan government in 2010 but unbanned by the courts in July.
He said the government is neglecting the region, and complained that jobs, land and resources go to outsiders from the rest of Kenya. "We have been made slaves in our own land," Ruwa said in Mombasa, the country's second-largest city.
Zanzibar, merged with Tanganyika almost 50 years ago into Tanzania, is now hearing Islamists call for a referendum on ending the union.
The MRC, which says it has more than two million members, argues that the former British protectorate should never have been integrated into Kenya at independence.
Ruwa believes the region has a strong case for independence, backed by historical documents which Kenyan authorities say are false. Although most analysts believe secession will never happen, they say Ruwa's movement could play a significant role as Kenya prepares for elections in March, five years after about 200 people were killed in tribal violence after a disputed poll.
Suleiman Shahbal, a businessman campaigning for election as Mombasa's governor, acknowledged the appeal of independence. "A lot of people at the coast feel the electoral process has failed us … that has led to the frustration that you are now seeing epitomised by the MRC," he said.
One of the festering issues is land. Much of the best property at the coast is owned by people from other parts of Kenya – a result, the MRC says, of land-grabbing by Kenya's first president after independence, Jomo Kenyatta. – © Guardian News & Media 2012