Theoretically with a 4-year degree you are able to apply for any job. It's getting hired that is hard. If you have long-term visa status that is going to help (basically married to a Japanese) otherwise your choices are going to be limited to language teaching. There is also IT work available, but jobs that don't require fluency in Japanese are harder to find.

My mothers working hours are 8 to 4 but she often works overtime. She may work from 8 to 6 or 8 to 8 sometimes even until 10, but she will clock out at 4 or 5 and work overtime for free.

Is that how it generally is in Japan?

In my experience, non-salaried people don't work overtime off the clock nearly as much as salaried employees.

Salaried? What does that mean?

That means you have a set monthly pay, and you are not paid by the hour. Hence the "salary man" who works 12 hours a day. Doesn't matter how many hours you work, people on salary don't have overtime.

My father is known for working 80 or more hours in a week since he is always on call. They pay overtime and also even double time after 80 hours.

I was wondering if there was a minimum wage in japan.

Not sure how accurate this is, but I got it from Wikipedia

In Japan minimum wage depends on the industry and the region. The lowest minimum wage for a region (Miyazaki) is ¥4,712 (~US$47.34) per day, and the highest minimum wage for a region (Tokyo, Kanagawa, Osaka) is ¥5465 (~US$54.91) per day. The minimum wages are set by the Minister of Labour or the Chief of the Prefectural Labour Standards Office. Recommendations are made by the Minimum Wage Council

okay so the highest seems to be about the same as in america. that is if the work day is 8 hours. if its longer than 8 in japan then it's less.

Every time I hear someone say this it makes me cringe.
It`s simply NOT correct.

A salary is a set amount of pay for a set number of hours of work each month. The standard is 8 hours of work a day on every workday for the length of the month. Generally around 170 hours, depending on the month. The salary is SET pay for every month - so even if there is a month full of holidays where you are only working 120 hours for the month - you`re still going to be paid the exact same amount as the month where there were 31 days and no holidays.

Anything over the set hours is indeed overtime. It is illegal to ask an employee to work over the set salaried hours for free. They must be paid for it.
There is nothing against an employee thinking that working for free might impress a boss or get them a salary raise based on dedication, etc - So in the end working free overtime is an employee choice. (And depending on the industry will actually do the opposite of impressing superiors...)

Working a salaried job is much better in the long run than a "by the hour" job, as your pay is guaranteed even if there is no work for a month. You will still be paid that set salary amount even if the boss calls it a day and lets everyone go home at lunch for a few weeks. (Which happens in some industries during slow periods.)
Salary or not has absolutely nothing to do with overtime.

The normal workday is around 10 hours - 8 hours of work, 1 hour for lunch, and 30 minutes before and after work for various things. When there is a lot of work, it can become much much longer. But anything above the normal workday is considered overtime.

ETA; Ack, I didn`t notice the year on that comment when I replied. Ouch.

I know I know...