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Have you checked this out? https://play.google.com/store/apps/details?id=com.atistudios.mondly.fa The best way to learn is to socialize with Persian people. Go to their gatherings. They are specially welcoming to individuals who are interested in leaning about their culture and their language. And that is pronounced "mo te shakeram".
So you speak Japanese, and you want to learn Persian? Nice combination m8! As far as I know, one of the few language learning apps that have such a feature is Mondly because they have over 30 languages available and I know for sure Persian and Japanese are available so you can basically set this combination. Don't know what you are using as your phone OS but found apps both for Apple and Android: https://itunes.apple.com/us/app/learn-persian-language-course/id1078881032?mt=8 https://play.google.com/store/apps/details?id=com.atistudios.mondly.fa
Meanwhile, did some digging, I manage to get a direct URL from their website with the mother language in Japanese and target language in Farsi: https://app.mondly.com/?mother_lang=ja&target_lang=fa - You should be redirected into the tutorial.
Have fun! Hope it helped.
Try this one.