Japanese school rules that force children to dye their hair black so they fit in with their classmates are facing a growing backlash, fuelled by a viral video campaign and a fast-growing petition.

Some 60 per cent of public schools in Japan require that all pupils submit a document called Natural Hair Certification, which confirms the natural colour and degree of curliness of their hair.

A new survey shows one in 13 schoolchildren had subsequently been “urged” by their school to dye their naturally brown hair black.

The survey of 1,000 children and teachers accompanies a new campaign masterminded by P&G’s Pantene shampoo brand, which also sells hair dye, to challenge the expectation.

Nearly 10 million people have watched the campaign video.

The issue of draconian hair rules in Japanese schools was highlighted two years ago when a pupil sued Osaka Prefectural Government for damages after being continuously forced to dye her naturally brown hair a more uniform black.

Critics say the rules reflect a deeply homogenous Japanese society where collective uniformity is valued over individuality.