Japan's government wants the country's office workers to shed their suits in an attempt to use less energy on air conditioning systems this summer.
The government's "Super Cool Biz" campaign encourages workers to wear outfits appropriate for the office yet cool enough to endure the summer heat.
Polo shirts and trainers are allowed, while jeans and sandals are also acceptable under certain circumstances.
The loss of the Fukushima nuclear power plant could lead to energy shortages.
The plant was severely damaged by the earthquake and tsunami in March.
The idea for summer officewear was first introduced in 2005 by the then environment minister, Yuriko Koike.
"When we started Cool Biz in 2005, people said it was undignified and sloppy," Ms Koike said at the fashion show held to kick off this year's campaign.
"But this is now the sixth year and people have grown accustomed to it."
Figures from the Cabinet Office suggest that more companies are getting on board.
In 2005, less than a third of 2,000 poll respondents said that Cool Biz had been implemented in their workplace. In 2007, the figure had risen to 47%, and in 2009 it had reached 57%.
The Environment Ministry's dress code suggests that men may consider wearing a pair of tight pedal pushers or carry a fan with them.
While there are no specific rules for women, the fashion show included ensembles for women.
Khakis, white trousers and airy polyester dresses all appear to be acceptable.
"As we are lacking electricity, the Japanese government is asking for a 15% reduction in electricity consumption," said current Environment Minister Ryu Matsumoto.
"This is not just about surviving this summer, but this is a big turning point for changing the way Japanese live and our lifestyle."
Last month, Japan's carmakers agreed to work on Saturdays and Sundays and move their weekend break to Thursdays and Fridays in order to use energy at off-peak times and help to avoid power shortages.
The Japan Automobile Manufacturers Association said the change was a way to "limit power consumption without disruption to production".