(ed. Somuka (Home Affairs Ministry) English pdf added] Joe Tomei here. This is the national website for applying for the COVID monetary support. You need to have your MyNumber up to date, be the head of household, and have resided in Japan for at least 3 months. All in Japanese and not yet connected to the local pages for this unfortunately. But if you cannot wait, you may want to work thru this page.
At my house, we are waiting for the mail application because we don’t have our MyNumber card updated, so people who do use the online portal to apply, please post in the comments your experiences.