Census takes place in Japan this year. If you live in Japan for a mid to long-term period, you must fill out the form and submit.
However, if you are living in an apartment, for example, as a short-term visitor which means you are willing to leave Japan in less than 3 months, you do not have to fill out the form. Please explain to the staff your circumstances, and you should be exempted.
On the other hand, if you are living in Japan, for example as a spouse of a Japanese citizen as a short-term visitor waiting for your certificate of eligibility for your Spouse of a Japanese National visa, you are an object of the census since you and your spouse are in the same household.
If you are required to fill out the form but refuse or even forget to fill it out, there is a fine for 500,000 yen or less. Please heed.