When I go study in Japan via MEXT Scholarship can I take my mother to live with me later with a Dependant Visa?
Yes, you can.
Once you have your student visa, you can apply at your local Japan embassy for her certificate of eligibility, and with that, you can apply for her dependant visa.
You can also do it from Japan. She can come with a tourist visa and you do the process from here. Although it is not recommended, as the process takes time and it may be risky