Where can I buy it? The English version?

You can buy the English physical copy at rightstuf, kinokuniya, amazon I think there might be a few more stores that sell it but I haven't been exposed to them yet. As for digital copies idk sorry

Hope this helps!

Thanks a lot! But unfortunately I’m not interested in a physical copy

Here you go! You can buy digital straight from the publisher's site.
https://www.sublimemanga.com/candy-color-paradox
They also have links to Kindle, Apple Books, Google Play, Nook, and Kobo!!

Thank you!