Only 55.1% of buses used by preschool facilities and others around Japan are equipped with safety devices to prevent children from being left behind alone, a government survey showed Tuesday.

According to the survey results released by the Children and Families Agency, the proportion stood at 67.4% for kindergartens and certified kodomoen kindergarten-nursery hybrids and 67.3% for nurseries.

The government made safety devices mandatory in April this year, following an incident in which a 3-year-old girl attending a kodomoen in the city of Makinohara, Shizuoka Prefecture, died after being left behind on the school's bus last September. While the government set a one-year transition period for installing the devices, it also called on facilities to fit them where possible by the end of this month, before the risk of heatstroke grows with the approach of summer.