Asking a current employer for reference for program abroad? Ethics concerns?

Basically, applying for a reputable teaching abroad program not in Japan. The program would take place, if I make it, after my employment in Japan would end (over a year from now if it happens). Wondering if asking a current or former employer/supervisor for a reference (a few short answers, not full LoR) is a violation of Japanese business ethics/laws.

Also, are there any specific cultural considerations if I ask a Japanese national?

Thanks for any advice if you’ve been in this situation!