Koseki touhon for half japanese

Hi,I'm half japanese &persian and I’m 27 now.
My mom passed away with suicide when i was 5month.
So i guess I should not be in moms koseki.
My older brother was born in japan and my dad is an iranian who got japanese citizenship now but i don’t have any connection or call with them.
I have only my mom’s brother’s number and i dont want to make trouble for him because we didn’t any special relation together.
But only me from my family living in iran and all of them are japanese now! I really need my japanese passport it’s my right.
How can i get help From my old uncle exactly from this situation?
Should I want a proven letter or something or he should go some offices in japan?
what is the process list?! Someone help me please…

Your best bet would be to contact an immigration lawyer or someone how knows the law and what you're allowed to do and the steps to take.

it is impossible, if your information is correct.
(be noted that it is not your right. you can be, if the condition is sufficient. and in your case, it is too late.)

but, you may try to find your mother's koseki.
to do it, contact to her brother, if you can communicate with him.
also, you can find your brother (and your father) when they are living in Japan right now.

Your first step is to contact your uncle, or if possible, your brother to help you get a copy of your mom's koseki. You seem to be unsure if she registered you or not.

If she did register you in her koseki then you can get a Japanese passport. If not, it's too late to get Japanese nationality but you can still get a Child of a Japanese visa.