An upcoming trade fair in Tokyo will showcase wearable devices that include underwear that can measure the wearer's heart rate, calorie consumption and back straightness.

The machine-washable garment, knitted with conductive metallic textiles, was developed by major underwear maker Gunze Ltd. in collaboration with NEC Corp.

According to the two firms, the metallic textiles serve as sensors for the health data and can quantify the degree of stoop. The data will be wirelessly sent to a smartphone automatically.

Via smartphone, the data can be stored online using NEC's cloud technology, enabling it to be used by businesses, including in a service in which a gym instructor offers advice to customers based on their postures and other health information.

The two firms are currently developing an app that will let users to browse their underwear data on their smartphones so that a prospective service for gym users can be launched by the end of March 2017.

The garment can be washed because the device that sends the data is detachable.

The underwear will be on display at the Wearable Expo to be held from Jan. 13 to 15 at Tokyo Big Sight.

Gunze aims to post ¥2.5 billion in sales from its wearable devices in fiscal 2020, which runs through March 2021.