just use your common sense.

WWI (World war 1) UK and JP are friends. The Uk Navy trains and sells ships to JP. The Brit Consulate is the closest (and still is) consulate to the Imperial Palace.
WWII (you guessed it) Japan moved into India (Britains slave whore) so Britain and Japan had some nose punching to do.
Most of the nose punching came from Japan and as taught by Britain (a small island nation) you don't give up, keep on fighting and even when you see a stiff upper lip, you should punch it good and proper.
Britain did not like this.
In an attempt to hold on to it's fortune (India) it sacrificed many of it's people to battle a far more determined people.
Thus you will hear a great many tale of why Brits hate Japs.
But in truth, the two island nations shared a great dream of world domination, and this is why, still to this day, both nations admire eachother with love and hate in equal measure.

Plus The Japanese REALLY love the Union Jack!

What about the saltire? :D

Two comments. First, while Japan threatened British India, they never entered its territory. (They did enter Burma, but that had been separated from British India in 1937.) The real impact on British dominions was the Japanese invasion of the British territories of Hong Kong, Malaya, Singapore, and Burma, and the Australian territories in New Guinea. There were also attacks against Australia itself. Also the Japanese managed to sink two British capital ships, the battleship Prince of Wales and the battlecruiser Repulse. Much of this happened within the first few weeks of the war.

Second is that you make it sound like Japan's split with Britain was precipitated by its movements into British imperial territories. Actually that split had happened some twenty years earlier, and the U.S. was mainly responsible. By World War I the U.S. was already highly distrustful of Japanese power in the Pacific, and after the war Britain was concerned that it could be drawn into a naval arms race or even a war with the U.S. To preserve good relations with the U.S., Britain eventually decided to abandon its Japanese alliance, which was officially dissolved in 1923 as a result of the 1921 Washington Naval Conference.

Wikipedia's article on the Anglo-Japanese Alliance has a more detailed history of the relationship, with pointers to further sources.

One of the more bizarre versions of "Britishness" occurs in the anime "Read or Die". In this timeline the British Library is behind an underground intelligence organisation with a huge military capability including submarines!:) . Amazing!

While everyone is different and have different opinions about things there are certain stereotypes that are popular. The one I hear the most is that Englishmen are all gentlemen which never fails to make me laugh. Many Japanese don't seem to understand what a chav is.

Then again,they might just prefer not to focus on it.

As far as I know Japan has good to reasonable relations with all countries except North Korea.

Yeah. That's what I thought. Although they did have a programme on a while back where they had a foreign people hour!