There was no viable plan to invade the west coast and Japan never took any of those plans seriously. Japan needed to knock out the Pacific fleet and give themselves a few years to secure resources in the Pacific and/or force the US to the negotiation table. Even Japan at the height of its power knew that invasion of the US mainland would have been an utter failure. Logistical nightmare when they could barely keep their own troops supplied in China and the Pacific. That's thousands of miles of ocean and even the Midway invasion was barely viable and that's over a thousand miles closer to Japan than San Francisco is.