Guest House managers must submit papers or a CSV file of the guests they have hosted at their short-term rental. Here are the due dates I have been able to find:

According to another host:

Submission dates are all the same countrywide. One minpaku system, one set of dates. 180 days from June 15, 2018- Mar 30, 2019. Going forward all annual 180 count gets reset April 1st. Only this past year was 180 days from June 15th.

Aug 15 (Jun & Jul rentals)
Oct 15 (Aug & Sep rentals)
Dec 15 (Oct & Nov rentals)
Feb 15 (Dec & Jan rentals)
Apr 15 ( Feb & Mar rentals)