A cheerful song by one of the most successful K-pop girl groups has emerged as a protest anthem for thousands of South Koreans rallying for President Yoon Suk Yeol's removal from office.

"There's a rough road ahead of us," sang the demonstrators in unison, gathered daily outside parliament since earlier this month, when Yoon briefly imposed martial law, only to reverse the decision after facing pressure from lawmakers.

Ahead of what was ultimately a decisive vote to impeach the embattled president on Saturday, protesters chanted mocking rhymes and sang K-pop in their daily demonstrations, with one song serving as a clarion call for his removal — Girls' Generation's "Into the New World."