Would it be possible to have the Japanese form ties with the Hawaiian monarchy before the coup and then have the IJN intervene to restore the monarchy after an alt-coup?
I do question whether, if Japan intervened to support the monarchy, the US would intervene. Not only is it difficult for the US to do, but the US also has a strong consensus against annexing Hawaii. The real problem with making this happen is, as I see it, finding a reason that would compel the Japanese to intervene. As others have pointed out, the IJN has much more vital jobs closer to home.
I agree with what others have said that Japan annexing Hawaii is, in 1893, really, really unlikely. Not only would it cause more opposition and be more expensive, but it would mean that Japan would need to base a naval squadron in Hawaii. In contrast, an independent Hawaiian monarchy could have its own squadron of coastal patrol ships and alliances with Britain and Japan to secure it.
I have to say, I find the idea of an Anglo-Japanese aligned Hawaiian monarchy continuing on into the 20th century a fascinating one.
fasquardon