Financial support if I can’t continue to work

Hi all!
Maybe someone was in a similar situation or knows more about this matter and can help somehow.

Last year in June I got a breast cancer diagnosis. In September I took 1 1/2 months off from work for the surgery (mastectomy) and recovery time. After that I continued to work for the same company.
My current contract is until April but I will start chemotherapy at the end of this month and the therapy will last about 6 months and after that radiation for a month.
I will not be able to work for this period of time so I know that my company will not renew my contract in April which is ok for me.

Now I have a problem to figure out where I get financial support from if I am absent from work and then lose my job (and salary) from April.

When I was absent from work for the surgery last year, I applied for the 60% of my salary from the health insurance I am currently insured with with my company (Shakai Hoken) and got the money for the 1 1/2 months.

Now my school manager says that she thinks my boss won’t allow me to be off for the next few months until my contract ends. But I am not sure how this should work because I can’t work if I get my chemotherapy (at least not on the infusion days and I don’t know how I will feel physically and my doctor doesn’t recommend to work while my immune system will be low) I want to focus on my treatment and not work while I get chemotherapy.
Now I don’t care if they fire me because I will be absent for a long time but then my manager said they can’t fire me if I am absent because of sickness. I am confused because do they want to force me to come to work?
Also I don’t want to quit myself because I am not sure if I can get any financial support from hello work or the health insurance then. (Not hello work as far as I know). Also I will maybe be able to work if I am feeling ok for at least a few days a week I just don’t know yet.

My manager also told me that she asked the National Health Insurance (the one I will be with if I lose my job)about financial support when I leave the company and they said they won’t pay me anything.

Now I read about shoubyouteate that they will pay when I am sick even when I left the company but I don’t understand how this should work because my company won’t pay their part to the health insurance anymore when I leave.

Any advice or idea what I can do?
If I don’t have any income or financial support I don’t even know how I should pay for my treatment.