Subway commuting may get easier for expectant mothers, with tests beginning Monday in Tokyo of a system that will allow them to ask willing passengers via a chat app to give up their seats.

Tokyo Metro Co., Line Corp. and Dai Nippon Printing Co. are conducting the test on the Ginza Line until Friday to check the feasibility of the service, which combines Line's messaging app with a system developed by Dai Nippon Printing.

The service is aimed at linking pregnant women with passengers who are willing to give up their seats to the women but who "would not notice their existence because they are looking at their smartphones," the three companies said in a news release in November when they announced the plan.

In the test, pregnant women can send a message to people who have pre-registered as their "supporters" on a special Line account. The message will reach only those nearby on the train, who can offer their seats by specifying their exact locations and letting the women approach them.

"By putting the service into practical use, we are aiming to create a system that is helpful not only for pregnant women, but also for disabled and elderly people," a Dai Nippon Printing official said.

The tests will be conducted in the last carriage of eight trains a day on the Ginza Line, which passes through central Tokyo, to check how well the system actually helps pregnant women get a seat.

The service developers are aiming to eventually create a system allowing pregnant women to carry a special device that, when its button is pushed, emits a signal alerting registered passengers that they are seeking a seat.