The British deployment marks the first time ever Japan's Air Self Defense Force has hosted joint exercises with aircraft from a nation other than the United States.
"This exercise aims to enhance tactical skills of the air forces and strengthen Japan-Britain defense cooperation. We do not have a specific country or region in mind," Japan's Defense Ministry said.
But they come at a time when Japan is becoming increasingly embroiled in disputes with North Korea over Pyongyang's testing of nuclear warheads and missiles that could potentially carry them.
Two of those missile tests have seen rockets penetrate Japan's air defense identification zone in recent months.
New security legislation
Koichi Nakano, a professor of Japanese politics at Tokyo's Sophia University, said the drills were a result of security legislation passed last year in Japan.
That allowed the country's Self Defense Forces to participate in foreign conflicts in the name of "collective self-defense," as Japan's pacifist constitution only allows it to act in self defense.
"The idea is that Japan will be able to collaborate further with the US and also other countries that do not necessarily have an alliance," he said.
Japan's Defense Ministry echoed that.
"Conducting this exercise in Japan will help in strengthening the UK's commitment in the Asia Pacific region and increasing other European countries' interest in the security situation in Japan and the Asia Pacific region," the ministry said.
Big test for Britain's air force
For Britain's part, the East Asia deployment tests its air force in a new way.
"This is the most ambitious deployment that the Typhoon Force has ever done. I think it's probably the most ambitious deployment that the Air Force has done to the Far East," said Wing Cmdr. Roger Elliott, who leads the Royal Air Force unit dispatched to Japan.
The RAF's Typhoon fighters are twin-engine jets capable of air-to-air and air-to-ground combat. They have been used in the UK combat operations in the Mideast in recent years.
The Typhoons will first operate out of Misawa Air Base, a joint Japanese-US facility in northern Amori prefecture on the main Japanese island of Honshu. They'll fly with four F-15 and four F-2 Japanese fighters as well as British tanker and cargo aircraft.
The UK-Japan exercise will wrap up on November 6, when the British planes head to Osan Air Base in South Korea for the first-ever South Korea-US-UK joint air force drill, South Korea's Defense Ministry said.
"The joint drill is called Invincible Shield and it is meaningful in that the UK is actively implementing a security pledge as one of the members of United Nations Command's strategic provider," a South Korean Defense Ministry statement said. United Nations Command was the alliance that fought the Korean War from 1950 to 1953.
The British deployment has not gone unnoticed in North Korea, which, through its Korean Central News Agency, said it was part of Japan's plan to become a world military power again.
But analysts say it's not just North Korea with which Japan has concerns.
Japanese tensions with China
Tokyo also is looking for allies in tensions with China, which have flared over Chinese maritime movements near the disputed Senkaku Islands in the East China Sea, which Beijing calls the Diaoyu islands.
"Increasing stronger cooperation with allies beyond the US is seen as kind of hedging against the rising China threat," said Benjamin Ascione, an expert on Japanese foreign policy at the Australian National University.
Nakano at Sophia University agreed, saying that said the Japanese government was trying to "fan fear" of regional threats posed by Pyongyang and Beijing to get more involved in military collaborations.
"That could be joint exercises, more collaboration in places like the South China Sea, or even the Middle East," Nakano said.