You need to remember the constraints of local languages when considering where you might go. i.e. speaking good English probably won't be much use to you in Finland unless you also speak Finnish. Similarly, in Belgium you'd need to be able to speak French in some parts of the country but Flemish elsewhere. (Although some European countries do have higher education institutions where the language of instruction for some courses is English, you'd need to be fluent in the local language(s) for you to be able to work with children to develop your plans).
So, assuming that the only languages you speak fluently are Japanese and English, you need to concentrate your enquiries upon those countries where English is the first language. That means that the UK, Ireland, the USA, Australia and New Zealand are among the countries that you should be considering, together with the English-speaking areas of Canada. It won't be an easy to task to find a suitable university (or potential business partner) in any of them and you'd also need to check up on the relevant visa requirements. However it seems to me that it would be totally pointless looking at a university in Helsinki if you don't speak Finnish, in Liège if you don't speak French or in Antwerp if you don't speak Flemish.