On a hazy day this week, a convoy of three white trucks is making its way through the streets of Nanjing, in eastern China. They are covered in huge red banners with black lettering that look like billboards from a distance. “Treating a ‘disease’ that doesn’t exist,” reads one. “Chinese classification of mental disorders still includes ‘sexual orientation disorder’,” says another. And the third simply asks: “For 19 years, why?” They slowly take their message across the Yangtze River, through a vine-covered ancient gateway, and past the New Street district, bustling with shoppers and office workers.