How to get long term visa for myself?

My father residing in Japan for more than 25 years and he is having the permanent residence.My age is 24.Please, can anyone help me how can I apply for the longterm visa?Earlier I have the longterm visa when I was young but Japan immigration has changed the rules for us that they won't give long-term visa to us as they are saying that after 18 we don't give long-term visa.Please help me I am in Japan right now.

so many information is missing.
Also maybe you better to ask your father to support you and check the options for you.

So immigration made things clear to you and now you ask advice to random people on a forum what you should do next. Guess what: we would send you to people in charge: immigration. There is nothing more to say. They make the rules, they know rules better than we do and they are the one who decide who stay and who leave. Ask them...

If

1. you were born in Japan;
2. your father was already a permanent resident at the time of your birth; and
3. you have been continuously residing in Japan since birth,

then you may have a shot at "Child of permanent resident" status. Otherwise, you'll have to get a student/work/whatever status like everyone else.

And if by "long term visa" you mean "Long-term resident" status, as you were told that is not possible.

you have been living on dependant visa .. now you are no longer dependant .

if you have a job and paying your tax ... you should apply for special permit or your father should apply for you.
this will be approved by ministry of justice if could prove good reason why you want to stay in japan.

you have been living on dependant visa

No. Permanent residents cannot sponsor for "Dependent" status (which is why a separate "Child of permanent resident" status exists).