Is it likely that you will join a Japanese company? Working cultures and practices may differ between Japanese and Western companies. Let's organize the points to check in advance.
The first point is to clarify the scope of work. Employment contracts in Japan often do not clarify the scope of work. Perhaps if you ask for a clear scope of work, it won't be written in your employment contract.
There are still few Japanese companies that have a JOB-type personnel system, and they work in a so-called membership-type manner. In other words, they do not overly clarify the scope of their work and are willing to help each other.
However, the ambiguity of work can be stressful for foreign nationals. Before joining the company, it is a good idea to confirm the scope and responsibilities of your first job, as it can be verbal.
The second is the provision of incentives. It is called a bonus in Japan. In some cases, this payment is ambiguous. Bonuses are not legally guaranteed to be paid. That's why you need to make sure you really get the bonus.
Finally, its is about company fringe benefit. The characteristic of a basic company is that the salary is a little cheap, but the welfare program is substantial. For example, it will be medical assistance and homeownership assistance. However, there is also the fact that foreign nationals do not use this benefit without knowing it.
The welfare menu of Japanese companies has become complicated these days, and there is currently no English version for foreign nationals. It's a good idea to check how much benefits you have, even if your salary is a little low.