By Agence France-Presse
The ministry wants 5.298 trillion yen ($47 billion) for the next fiscal year from April, the seventh straight annual increase and 2.1 percent more than last year.
Among the items on the defence ministry's shopping list are two sets of US-made Aegis Ashore missile defence systems to defend the country against North Korea's nuclear and missile threats, with a combined price tag of 234.3 billion yen.
It also wants six more F-35 fighter jets and two E-2D Hawkeye radar and maritime aircraft, with plans to expand the air force patrol team by adding 30 servicemen to a current team of 830.
The budget request came hot on the heels of the ministry's annual defence review, which said North Korea still poses a "serious and imminent threat" despite a diplomatic detente earlier this year.
After the historic June 12 summit between US President Donald Trump and North Korea's leader Kim Jong Un in Singapore, there has been little tangible progress in denuclearising the Korean peninsula.
In recent weeks, Washington-Pyongyang relations appear to have taken a turn for the worse, with Trump abruptly scrapping a planned visit to the North by Secretary of State Mike Pompeo.
The defence review also took aim at China's rise as a military power, saying Beijing was sparking "strong security concerns in the region and international community, including Japan".
Tokyo is wary of Beijing, which is seen by several countries in the region as becoming increasingly aggressive over various sovereignty claims, including a long-festering row with Japan over small islands in the East China Sea.
For its part, China announced in March an 8.1-percent defence budget increase to 1.11 trillion yuan ($175 billion) for 2018, as it bids to modernise the world's largest military.