You said that if you have a junior college diploma, it is ok to be admitted to a junior in a Japanese university, but if you want to change your major, it is not to say that you can't, but if you are admitted, you must be at the same level as a sophomore in the same major in that university before you can be admitted. So if you want to change your major, you may have to do a lot of things to reach this level. Moreover, Japanese universities basically have a corporate system, so it has nothing to do with the school, so don't worry.

And as a school, I also hope to accept a student with the same major, otherwise it will be difficult to manage, right, so you have to think it over.