In the usual show of unity, all three Japanese majors will have at least some production up by mid April. Honda told The Nikkei [sub] today that it will resume auto assembly at its two domestic production plants in Saitama Prefecture, near Tokyo, and Mie Prefecture, western Japan, from April 11. The making of parts for overseas production will begin on April 4.
From what we hear behind the scenes, a large part of the restarted production relies on existing or very slowly arriving new parts. Depending on the tenuous parts situation, production can stop at any moment. Supply of stable power is a growing concern. It is generally understood that anything resembling normalcy is not expected before some time in summer.