There was a time in Japan when courtesy was second nature. If you saw an elderly person, a pregnant woman or somebody on crutches, you would leap up and offer them your seat. These days, you pretend to be asleep and avoid eye contact at all costs.

But the spiralling decline of train-seat etiquette may be about to end with the arrival of an elite, fearless and impeccably polite “manners squadron” — to be unleashed on the Yokohama underground network in an attempt to avert a breakdown of the “Japanese way”.

The unit's mission is simple: to patrol the length of the train and make sure that any seats — highly prized on Japan's packed commuter lines — are vacated by the young and offered to those who need them.

The officers will have no legal authority, no powers to fine and virtually no practical sanction at all. Their success will depend entirely on the high visibility of their bright green uniforms, and their capacity to charm or shame the sitter into becoming a stander.

As with any decent crack military unit, the Smile-Manner Squadron has been handpicked from a wide field of raw recruits. Volunteers were encouraged to enlist via a series of interviews and essays.

The hopefuls were aged between 30 and 80 years old but, said a spokesman, the squadron will consist almost entirely of officers over the age of 60. The group will be split into pairs, paid a modest $14 per day, and sent on their way to rebuke, chide and embarrass.

But, for want of a further signal of declining standards in a once-polite Japanese society, the officers will be accompanied by a younger body-guard — as a precaution against an explosion of rage on the part of a seat-hog unwilling to do the decent thing.

The creation of the squadron has been welcomed by prominent proponents of the theory that Japanese politeness is waning. Taizo Kato, a psychologist at Waseda University, said that the Smile-Manner Squadron “symbolizes the collapse of the Japanese mentality and shows that we have reached a point where citizens are not aware of basic human manners.”

Nobuhiko Obayashi, a polemical 70-year-old and author of the book "Why don't young people give their seats to the aged?," said the fault lay with parents for not scolding children more effectively, and with society for making many young people too shy to engage in the simple public interaction of offering somebody a seat. “Young people do feel the need of having manners in their hearts,” he added, “the experiment will give people who are too shy a chance to communicate.”

But the establishment of the squadron has not been without controversy. Even among the likely beneficiaries, there are serious doubts. “Vacating seats is a matter of each passenger's free will,” said an 81-year-old. “I find the idea of telling people to get up unnatural."