All public high schools in Ehime Prefecture decided en masse to require advance notice from students who intend to participate in off-campus political activity, the prefecture's board of education said Wednesday, though it has denied ordering the schools to do so.

The decision was made by each individual school, according to the board, and comes as Japan is set to lower the minimum voting age to 18 from 20 this summer. The requirement is sparking concern that it could deter students from taking part in events such as political rallies out of fear they would have to reveal their political beliefs to their teachers.

Such a move could further deepen political indifference among young people at a time when it is crucial for the country to raise political awareness in its youths ahead of the looming Upper House election this summer, experts say.