In 1942, they bombed an oil field north of LA. Balloon bombs were launched, and 25 were found in CA, but none caused injuries. And then of course, various ships were attacked. Aside from these, it doesn't seem like there was any real attempt at attack or invasion. Why is this?
Distance, mainly. The distance from japan to hawai'i is almost the same as the distance from hawai'i to california. Without establishing a line of supply ships (and ships to protect them) spread out across the entire pacific ocean, there was no way to actually fly that far in the planes they had. It just wasn't worth the effort.