Britain has made the exporting of education a national strategy. It’s a strategy that has met the needs of Japanese parents, especially those with high incomes, who want their children to receive a high-level education in English.

Of course not. Such inroads will be seen as an invasion threatening the whole "culture" by the people and the Ministry of Education, Culture, Sports, Science and Technology whose role it is to protect it.

The quality of your education is more important than the certificate you get. State education systems are welcome to compete, but are usually underfunded. In the end, a high quality education, state or private, comes down to individual, inspirational teachers and the application of the pupil. Parental support and well-resourced schools help, but you get more out of your education if you are motivated to engage with the courses that matter to you by a good teacher.

The gap between underfunded state and well-funded private schools may be narrowing a bit, as so many resources are now available online. But kids still need to be motivated to get the most out of their education. Despite the extra cost of private schools, kids are as likely to chance upon a really good teacher in the state sector as in the private sector, as many really good teachers work in state schools for ethical reasons. Parents do like to see the other stuff though - better behaviour, smaller classes, lots of modern tech.

That's generally. In Japan, English lessons are uniquely problematic.

Japan's unusual relationship with the English language is a blessing and a curse. Languages are tough, and Asian ones are amongst the toughest of all. Bluntly, they require more learning than Western ones. Unlike many countries, you can live a happy first world life in Japan without English. The American occupation had a socio-political and economic impact but did not last long enough to have the linguistic impact of the British colonisation of India or many African countries. In a developing/third world country, learning any variant of English, had/still has a financial career benefit that motivates learners. And very few people outside Japan speak Japanese.

That leaves Japan more linguistically isolated than much of the planet. As the UK is discovering with Brexit, isolation is expensive in all sorts of ways. I would guess that Japanese parents feel that they can fix this by sending their children to international schools, dodging any lack of skills or emphasis on English in Japanese state schools. There may simply not be enough fluent bilingual teachers in state schools in Japan.

Their kids might not appreciate the extra work, but the skills that benefit people the most from their education are practical ones that they will use throughout their lives (cooking, social skills, basic maths and literacy), the ones they need for specialist interests/careers (advanced maths or science) and fluency in a foreign language. In these areas, investment really counts.

I don't think Britain has a national (governmental) strategy on exporting education (and even if they did, it wouldn't matter, as they would be lousy at it). British universities do rely on the larger fees they charge foreign students. British private schools are also exporting their brands for financial reward. British teachers (like British doctors, nurses, techies and engineers) are simply escaping the UK.