Passport validity for zairyu extension

Hello all,
I'm in Japan on a "Spouse of Japanese National" zairyu card, and I'm starting to prepare for my first renewal. I understand that the renewal might be for anywhere from 1 to 5 years depending on the whims of the immigration office (or at least factors that I don't know). My home passport expires in June of next year. Is there any benefit to renewing the passport a year early, ahead of renewing my zairyu card, as a way to raise my chance of a longer term? Is there any policy of not extending residence status beyond the validity of your passport? Thanks!

If you had less than 6 months left on you passport. The Expiry date might matter. Other than that. No to all your questions.

In addition to above, if you plan to travel outside Japan anytime soon, it is best to have you passport renew as soon as possible.
Most airlines require at least 6 months validity on the passport. Exception may be given if you travel back to your home country, but then again who knows.

Residing in Japan with valid status, nearing expired or expired passport should be no problem to Japan immigration. Though renewing or changing status with expired passport may post problem with your application.

However, decision on how long your status period extension will be granted will have nothing to do with your passport validity.

passport date is not import.

http://www.immi-moj.go.jp/english/tetuduki/kanri/shyorui/14.html
Present your passport or certificate of status of residence either are ok.

OP said the current one is valid TIL June of next year - that is plenty of time. And having a passport that is valid longer doesn't do anything for raising the chance for a longer resident status.

If you had less than 6 months left on you passport. The Expiry date might matter.

No; the expiry date of the passport never matters. In fact, contrary to what the simplified information on the immigration bureau's website says, you don't even need to have a passport when you apply for an extension of your period of stay (if you don't have one, just submit a letter stating so).

Passport is a travel document and useful ID, but you don't need to have one if you are not travelling. Certainly no issue with a near-term expiry when applying for status of residence renewals.