In early September, the education ministry issued a notice to boards of education nationwide asking schools to let students leave their textbooks and other study materials at school — the practice known as okiben in Japanese — to reduce the weight of their school bags.

While some students and parents welcome the move, others worry that it could lead to problems such as students studying less at home or their belongings getting lost or damaged.

"I used to always feel tired because (my backpack) was really heavy," said Fuku Kutsuwa, 9, a fourth grader at Gifu Elementary School in the city of Gifu. "Now it's light, so I don't get exhausted even if I run." Her backpack only contains five or six textbooks.