During his speech, Modi said he was told by an "Indian family" in Japan that students and teachers there together clean and mop up toilets.
"They said it was part of character building. How do we build national character," Modi said.
Referring to his Independence Day speech in which he referred to absence of toilets in some schools, particularly for girls, Modi said it was a very important task.
"I need help from every school. An atmosphere should be created," he said.
Answering a query, Modi recalled his visit to a primary school in Japan and said there was no teaching but 100 percent learning.
He said children were part of learning process and were very disciplined.
He also said parents do not come to drop their children to schools in their cars and there was a collective effort to usher children into school, ensuring equal treatment to all students.
"I noticed there was scientific temper in students. They have been nurtured in that manner," Modi said.