At the Mirai's heart is the latest iteration of Toyota's fuel-cell stack, which generates water vapour and up to 114kW of power by combining hydrogen stored on-board with oxygen extracted from the atmosphere.
Under the bonnet there's a 113kW/335Nm electric motor that's hooked up to both the fuel-cell system and a nickel-metal hydride battery pack out the back, which is used to store excess energy and anything recaptured through regenerative braking.
There are two hydrogen storage tanks storing a total of 122.4 litres worth of the gas under exceptionally high pressure (70 megapascals). With both tanks filled up, the Mirai has a claimed range of 650km under Japan's JC08 testing standard.
At 1.535 metres tall, 1.815m wide and 4.89m long, the Mirai is not a small car — it's around nine centimetres longer and seven centimetres taller than the current generation Toyota Camry. All up, the front-wheel drive Mirai weighs 1850kg.
According to Toyota, the Mirai's side profile is meant to resemble a water droplet. Flat panels help to hide most of the car's undercarriage and enhance air flow around the Mirai.
The car's large air intakes are designed to help feed vast quantities of air into the car's fuel-cell stack, as well as help cool the system down.
Standard fittings on the car include LED headlights, 17-inch alloy wheels, lane departure warning, interior air purification system, blind spot monitoring, heated front seats and steering wheel, eight-way electric adjustment for the front seats, and a collision detection, warning and mitigation system.
On the inside, the Mirai features seating for four people, a lengthy digital instrument display that sits high up in the centre of the dashboard, a 4.2-inch entertainment and navigation screen, and capacitive buttons for the climate control system.
Unlike most previously available hydrogen fuel-cell cars, the Mirai will be available for purchase. Sales start in Japan on December 15 with an asking price of 7.24 million yen ($71,300).
Sales targets are modest, to say the least, with Toyota planning to shift just 400 units in its homeland by the end of 2015.