regarding to the school system in japan

If I'm a high school graduate here in the Philippines and I'll go to japan to study, will i go back to being a high school student?

I'm currently 17, and my mom want me to live with her. I'm planning on studying there for college but my ma'am said I'll go back being high school.

Your question is too vague to answer.

Does you current high school diploma allow access/entry to Japanese university level education?

Do you speak and read Japanese at a 17yo level? Otherwise attending a regular Japanese high school would be difficult.

So your mother is living in Japan while you are in your country, right? If you go to a high school, I wonder which visa you can apply as a high school student. The fact that you are already 17 and you don't live with your mother could be meant that you are not eligible to apply a dependent visa.

If you apply a student visa, you need to be permitted to go to a school by passing the entrance exam in Japanese. You need to go to Japan as a temporary visitor to take the exam at first, applying an another visa for that.

So I think being either a Japanese language school or university student seems to be more practical as long as you are eligible with your high school deploma.