Passport validity

I will be traveling to Japan this August for 2 or 3 weeks and my passport will expire in December. Does anyone know if Japan requires a passport to be valid for a certain period of time past your visit? Some countries require a passport to be valid for 6 months past your date of visit. I've looked online and cannot find anything that explicitly states Japan's requirements. Anyone know?

"Anyone know?"
Yes, the Japanese Embassy or Consulate in your country knows.

Does anyone know if Japan requires a passport to be valid for a certain period of time past your visit?

Unlike some other countries, Japan does NOT require the passport to be valid beyond the date of entry into Japan.

As long as it is valid on the day you leave Japan, you are fine :)

I think it all relates to which country you come from, Japan customs will stamp the passport for how long you can stay in Japan, so at least your passport should be valid pass that date another 3 months, but I guess like other countries it's 3-6 months, for HK it's 90 day stay duration, and it is required at least 6 months validation of the passport.

Who know what will happen, you might have to stay longer due to certain situation.

No, your nationality doesn't matter. Japan does not require X months of passport validity like many countries. If your passport is valid until the day you leave, you're just fine.