A Japanese venture has developed a smartphone case designed to help parents protect their children from becoming addicted to the mobile devices.

The Kobe-based company Momo Ltd. plans to begin selling the smartphone case in late August. Called the Otomos, it allows parents to set time restrictions and prevent children from using their phone while walking.

A child's smartphone is fixed inside the case with a screw and cannot be detached without a special tool.

With a downloaded application, parents can use their own smartphones to control their child's daily phone usage. If their kid tries to exceed the limit, the phone automatically enters sleep mode.

For parents who don't have a smartphone, the settings can be made from a website.

The case can also deactivate the smartphone if it detects walking motion. Automatic messages can be sent to parents' smartphones if it senses a huge shock, such as through an accident.

"We developed the product after hearing many views and concerns of parents who have children using smartphones. All you have to do is just attach the case, so it is very easy to use," said Masato Otsu, the 37-year-old president of Momo.

The company is expected to charge around ¥500 per month for a two-year contract that includes the monitoring service, the smartphone case and the cost of the app. Customers can apply for the service at mobile phone shops or at its website.