Shintaro Ishihara is known in Japan for his outspoken remarks
A group of French speakers in Japan are suing the governor of Tokyo after he described French as a failed language.
The 21 teachers and researchers are demanding compensation and an apology for the "insulting remarks" from Governor Shintaro Ishihara.
Mr Ishihara is accused of saying he was not surprised French did not qualify as an international language, as it was "a language which cannot count numbers".
The veteran politician is well-known for his outspoken comments.
He has previously drawn criticism for saying the Nanjing Massacre, in which hundreds of thousands of Chinese were slaughtered by Japanese troops in the 1930s, never happened.
His latest controversial comments came during the inauguration of a university building last October. Among the audience were French professors who had opposed his government's integration of five schools to form Tokyo Metropolitan University.
"I have to say that it should be no surprise that French is disqualified as an international language because French is a language which cannot count numbers," he said.
Numbers in French can be complicated for beginners, especially combinations which make up numbers such as 94, which translates as "four 20s and 14".
The group taking Mr Ishihara to court, who include French and Japanese nationals, are seeking a written apology and 500,000 yen (£2,545; 3,683 euros) each. They say his comments "hindered their economic livelihoods".
Brendan Marcus, who teaches at a private French school in Tokyo, is one of the plaintiffs.
"For someone of his public stance, it's quite unacceptable," Mr Marcus told Reuters news agency.
"When you know how many French scientists and mathematicians throughout history have made important contributions, [his remarks are] not appropriate."