I was moved to Iran when I was 5 from Japan. my father is Iranian and my mother is Japanese. I recently got my new valid Japanese passport from the embassy of Japan in Iran. I also did the paperwork for Japanese nationality in embassy a few months ago but no response. I'm turning 22 this year is this mean I lost my Japanese nationality? I will be 22 in August. also I can't renounce my Iranian nationality til the age of 25.
If you are a Japanese citizen, you will stay a Japanese citizen until you take an action that revokes it.
Within two years of turning 22, you're supposed to declare if you want to stay Japanese or renounce your other citizenship, but the law has a provision that assumes you will stay Japanese if you do nothing:
If you fail to make the choice of nationality within the above-mentioned period, you shall be deemed to have declared that you choose to be a Japanese national and renounce the foreign nationality
That said, there is no reason to wait. Go to the Japanese embassy, inform them that you wish to stay Japanese, and they will advise how to handle renunciation of your Iranian citizenship. The fact that you can't formally renounce it until 25 should not be an issue, since there are some countries like Belgium where you can never renounce it.