Tens of thousands of Hong Kong residents paid tribute on Sunday to a man most did not know, a 35-year-old protester who fell to his death outside an upscale mall late Saturday after unfurling a banner that denounced the extradition bill. The police characterized his death as a suicide.

The man was a mystery to many, an ordinary protester who was identified by the police only by his surname, Leung. But this much, the protesters knew: He wore a yellow raincoat.

The raincoat, and the harsh criticisms of the government inscribed on its back, became a motif in the demonstrations on Sunday.

Mr. Leung had been perched for hours on Saturday on the roof of a mall near the Hong Kong government complex. Shortly after 9 p.m., he climbed onto scaffolding on the side of the building, the authorities said. But as firefighters tried to rescue him, he fell, according to the police, landing next to an inflatable air cushion that had been set up to catch him. He was pronounced dead at a nearby hospital.

Many protesters carried flowers to mourn Mr. Leung, whom they referred to as a “warrior,” “hero” and “martyr.” They chanted his slogans, calling the police “coldblooded” and saying that Hong Kong’s chief executive, Carrie Lam, was “killing” the city. Some wore yellow raincoats in his honor.

At night, protesters held a vigil for the man, holding candles and waving mobile phone flashlights. Perry Chan, an artist, stood with an easel painting an image of the crowd. In one corner of the painting was the now widely-shared image of the man in the yellow raincoat.

Emily Liu, a banker originally from mainland China, took her five-year-old son to the memorial because she wanted to show him what was at stake in the battle over the extradition bill, she said.