The Japanese Defence Ministry is considering theh purchase of the F-35 joint strike fighter as its main combat jet after giving up a plan to buy additional F-2 aircraft.
The ministry plans to list the procurement costs for the next-generation jet in its budget request for 2012.
The ministry has requested 680m yen ($80m) from the 2011 budget to obtain information on the capabilities of the F-35.
Japan has been trying to upgrade its F-15 Eagles and buy additional F-2 fighter aircraft due to the delay in the development of the F-35 programme.