Work in a Konbini without high school degree

Ok so, i went to high school but didn't finish the last year because of health issues. I managed to get a student visa for language school in Japan. My question is, i can find a part time job (for example convenience store) without high school degree in Japan? Is that a requirement?

You didn't finish high school, so are you going to finish it, or get a certificate of some sort, or do you just drop out? If you can't even finish school in your country, I assume you are from US, then it's tougher to study in Japan. How good is your Japanese skill? They might hire you if you are bilingual, but you need to be able to communicate with them.

"I managed to get a student visa".
Does it mean you get a student visa for language school without graduating high school ?
some information indicates that high school is compulsory in Italy.

I have to wonder about your long-term plan.

Without a high school diploma, university isn't possible. Without a university degree, your chance of getting any work visa is very low. Without a visa, you go home at the end of your course.

It should be possible to get a part-time convenience store job, but your long-term chances seem dim.

If you can go back to school and finish your diploma, it will open up many options to you.

Requirements are:
- Work visa or work authorization for those on Dependent visa or Student visa
- Being able to speak Japanese fluently (no, you cannot work there if you can only say YES, NO, or Thank you in Japanese), also better know some keigo...

There is no way to get a work visa for working in a konbini once you finished school.

AFAIK, part-time work is a permitted activity if it fits within the restrictions like 28 hours per week. If you can read the news, you might know "28 hours" might just be a nominal number of hours you get paid for.

Being positive: not all countries require or have people doing all years of high-school before university, so that might not be a problem.
Being realistic: What is your actual plan? Once you finish being a student, you are unlikely to qualify for a status of residence irrespective of your Japanese ability. For 99% or people you still need a university degree and skills eligible for a work visa (one of many categories). Graduating a Japanese language school wouldn't acheive that.

You don't have to be a high school graduate to work at a convenience store in Japan. In fact, a great number of part-timers at convenience stores are high school students who are yet to graduate.

With that out of the way, if you wish to enroll in a university in Japan, you need to have a high school degree or an equivalent. It's not necessary to have attended the 3 or 4 years of high school, but for example, you need to pass some exams to get the certificate proving your skills.