I already said this before, but all I did was provide a list of web stores where foreigners can purchase the Japanese physical format CD of Mew’s new album.
As someone living in South Korea, I’m able to access the Japanese iTunes store.
I had no idea it was that difficult to use Japanese iTunes in other countries, because it’s quite easily accessible in Korea.

In Japan, they release the physical format CD the night before its official release date.
Fans who live in Japan will be able to get their hands on the CD right on April 21st. This is an old custom for them.
The reason Japan is so unique in this way is because they’re #2 in the worldwide music market.
Even the price of their albums is twice the cost of other countries.

In the worst case scenario, you might only be able to get the bonus track that isn’t on the physical format by buying the entire album digitally on Japanese iTunes.
https://itunes.apple.com/jp/album/+-bonus-track-version/id956107411
It’s not possible to only purchase the bonus track individually. It’s possible that you’ll have to spend 1,600YEN for the entire MP3 album for that one bonus track, even though the cost of the bonus track on its own would only be 250YEN.