Job in Japan

Hello,
I have been searching this forum for advices, but couldn't really find an appropriate answer, so I post a new question.

I have the impression that it is difficult to live in Japan for a foreigner who isn't an English-speaker...

When I asked for advices about searching for a part-time job, both my former host families and my japanese teachers told me "It would be good if you became an English teacher or tutor",

So where could I be able to find a job wich doesn't require to speak english?

Most foreigners in Japan are not English speakers.

I've seen many foreigners working at restauarants, supermarkets, and convenience stores. Are those the type of part-time jobs you're looking for?

Oh, well during my stay I haven't seen a lot of foreigners working in conbini and shops, save from the french or italian restaurans where I have been, that's why I asked.

Is it easy to apply for jobs like that (such as cashiers, waitress or shop assistant) for a foreigner on a working-holiday visa, who has to go to school and doesn't have 100% fluency in Japanese?

Most places to work in Japan require Business level Japanese or JLPT N2, but a lot of other places will hire if you have basic conversational level. Whats most important is that you can communicate with people - doesn't have to be perfect. There are a lot of non-English speakers living and working in Japan - but most of them seem to get jobs through connections.