Child of Japanese National Visa question

I want to know if it's possible to get a Child of Japanese National Visa if my Father is a Japanese National even if my parents weren't married. I'm 23 years old and just graduated college and thinking of a better opportunity in Japan. Thank you!

Yes, the only requirement is that your father was a Japanese citizen at the time of your birth (as opposed to, for example, a foreigner who obtained Japanese citizenship afterwards).

Hello Firas, thank you for answering.

My Father is a Japanese at birth. My only concern is He is married in Japan and I don't know if it will still be okay? Or the only problem is getting my Father to acknowledge me? My only real communication with my Father was at birth until 1yr old. And only recently I met with Him 3 months ago when I visited Japan. And I've read in the internet that my Father should be capable of supporting me, but I'm afraid he is a Senior Citizen now and passed His business to His two daughters and is only living in pension now if I'm not mistaken.

Repeat: the only requirement is that your father was Japanese. Of course, you must be able to demonstrate that. If you want to know what kind of proof is required, ask the Japanese embassy/consulate where you plan to submit your visa application or consult its website.

To dear Firas:
You look not aware why the original poster asks about father's acknowledgment.

To dear kevin:

It seems
that your father's acknowledgment makes it possible
for you to acquire the status of residence
as a child of a Japanese national.
(A status of residence and a visa
are sometimes confused by ordinary people,
both in English and in Japanese.)

Firas:
the only requirement is that your father was a Japanese citizen at the time of your birth

However,
he and your mother were not legally married at the time of your birth,
so he is not naturally considered
to have been your legal father at that time.

To acquire
the status of residence of "Spouse or Child of Japanese National",
you should be
the spouse of a Japanese national,
a child specially adopted by a Japanese national
or those born as the child of a Japanese national.

He was a Japanese national at the time of your birth.
Child acknowledgment has retroactive effect from the time of birth.

Therefore,
by his acknowledgment,
you become a person who was born as the child of a Japanese national,
then you can acquire this status of residence.

Because you have reached the majority (i.e. you are a legal adult),
your consent is necessary
for someone to acknowledge you as his/her child.

I've read in the internet that my Father should be capable of supporting me

That is not for acknowledgment.

When the parents of a child who has not reached the majority
get divorced,
the probability of financial sponsorship is a key factor
to decide which parent should succeed
the rights and duties to raise the child.

Once becoming legal parent and child,
you father and you have a duty to support each other.

When he needs nursing care for his daily life
but his child, sibling or grandchild cannot help him,
you may have to assist him.

He is married in Japan
he is a Senior Citizen now and passed His business to His two daughters

Has he told his family members and other relatives
that he actually has a (non-acknowledged) child outside the family?

When he acknowledges you, a problem may arise in the future.

After he and you become legal parent and child,
if he dies while you are alive,
you are an heir of him,
which may lessen another heir's share in the inheritance.

A person entered in a family register
and his/her spouse, lineal ascendant and lineal descendant
can confirm the matters entered in that family register.

The fact that he acknowledged you
is entered in his family register
(i.e. the family register where he is entered).

So,
a daughter of your father in his family
can know the fact through the family register,
so can her legal husband (if there is any).

Acknowledgement may or may not be one of the things that are required in order to demonstrate eligibility; I think such things are better discussed with the embassy/consulate and not here, as is is ultimately they who decide what is acceptable.

I think Firas's answer is appropriate. it is very delicate and serious matter.
my advise is "tell your hope to your father".
if he agrees with you, he (and you) hire (or consult) a lawyer to take necessary paperwork to get a visa.
( I think that collecting all documents is not easy for you.)