There are lots of native speakers of English in Japan, but they do not all speak the same way. Each different way of speaking is called an “accent”. Native English speakers do have preferences for particular accents, and they often have an objection to some other accents.
Whether you are a native English speaker or you are just learning English, the big variations between regional accents may pose confusion and misunderstanding. Sometimes, the accents may be so different that communication is impossible.
Which accent are you accustomed to, and why?