Pension Insurance as a student

I have been living in Japan as a student about 2 years.

I found a job and company asked me to send some documents regarding the visa change application.

One of them is pension insurance number, since I don’t have it, I went to pension office.

The staff told me that I don’t have a pension so to get a number I have to get the pension first.
Which seems logical so far.

The problem starts with; as a law, Japan requires you to pay pension for every month you stayed in Japan. Which is around 15000 yen per month. So they asked me to pay 360000 yen in total.

I told them I cannot pay it, so they applied for some discount but I will learn the amount one week later when the documents arrive to my house.

Considering I am a student who can work no more than 28 hours a week and just applied for a job to be a full-time worker,

Do I really need to pay this kind of money?

I mean law is law but how can I be expected to pay pension as a student or someone with income lower than 1,300,000 yen a year.

Is there something I can do about it?