Jetstar Japan will begin services on 3 July, six months ahead of schedule.
The airline, which is a joint venture between Japan Airlines, Australia's Qantas Group and Japan's Mitsubishi Group, will be the first low-cost carrier to operate domestic flights from Tokyo.
Based at the capital's Narita airport, Jetstar Japan will serve Osaka, Sapporo, Fukuoka and Okinawa on 3 July. It will start with a fleet of three Airbus A320 aircraft.
"In a country that's never had a true low-fares domestic network, the ability to travel for an average of 50% less will open up new places and opportunities," said Jetstar Japan CEO Miyuki Suzuki.