"We conducted a survey in 2007, and many ladies requested for women-only lavatories," says an ANA spokeswoman.
From March 1, a women-only lavatory will be available at the back of each aircraft. The lavatories on board ANA's Airbus A320s and Boeing 737s will remain unchanged as these aircraft have only three toilets each.
The gentlemen, however, are not strictly barred from using the women-only lavatories. ANA says that they may do so when feeling unwell, or if there are very few female passengers on board.
The Japanese airline is not the only carrier to introduce toilets exclusively for the ladies. Korean Air has women-only lavatories on their planes, and female passengers on board Japan Airlines' aircraft get first priority in some toilet queues, says the ANA spokeswoman. Virgin Blue's long haul operations, V Australia, was also reported to have women-only lavatories on board.
As to why women travellers want female-only toilets, ANA's spokeswoman says they are tired of long queues for the lavatory. A handful of women also told the airline they won't queue up for a toilet if there are men in the queue - but the airline, being typically Japanese, is too polite to draw any conclusions from this.
So how did the guys react to ANA's plan? The carrier says 70% of male passengers it surveyed say they don't mind it, and some gave the idea the thumbs-up because it means less time queuing up after the ladies for the toilet.
Now that's what I call gentlemanly behaviour.