passport

My daughter and I are going to Japan from Sydney soon for 2 weeks.(We live in Sydney. I am Japanese and my husband is Australian)
I just remembered now that last time when we went back, we were told to get her Japanese passport if she is a dual passport holder. She entered Japan with her Australian passport given landing permission as a tourist.
I totally forgot about getting her new Japanese passport. We have no time for that.
Can she enter Japan again like last time? Or will there be any problems?

Nobody knows, it's up to the immigration official at the port of entry.

Well, she will certainly be allowed to enter Japan, as it is a core principle of international law that countries must admit their own citizens. But there may be some penalty for not using a Japanese passport as required, and some wait time at immigration while they ascertain her citizenship.

Travelling on an Australian passport the visa waiver programme applies. Entry should be no issue.

If she wants stay 90 days or less with no visa, then Aussie passport would be fine.

If she wanted to stay 91 days or longer with no visa, then the Japanese passport would be required.

If she wanted to stay loner than 90 days on a Aussie passport, then you'd require a visa.

Thank you very much for replying to my question!
We will be staying for about two weeks, so I really hope she can enter Japan using only her Australian passport.

I don't see how it'd be an issue. She has to go into the foreign passport line is all. Unless you told them, how would they know she's a Japanese citizen? Why did they tell her she had to have a Japanese passport the first time?

When we went to Japan about two and half years ago, my daughter was asked if she was a dual citizen. She said "yes" and was told to enter Japan with a Japanese passport next time. I totally forgot to apply for it.

When she was small, she went to Japan with her Japanese passport. Then I forgot to renew it for her and have kept forgetting until now.

If they ask you could always just say "no"... or say yes, and explain that you didn't have a chance to get the passport. They definitely wont deny her entrance just because she used her other passport, but it's probably easier if you don't bring it up at all.