Soon after Pearl Harbour, and through much of The Pacific Campaign, I assume the US government had a plan for if or when they invade and conquer Japan? I'm guessing genocide was never considered, so what did the US government wish to do with the country if they had full control over its landmass, military and government?
Would they have annexed Japan and made it either a state or an overseas territory? Give parts of it to China (assuming China doesn't conquer parts of Japan itself) as a political move or would they have actually granted it full independence at some point?
And just to clarify, this question isn't what would have happened if the US conquered Japan but instead what the US WANTED to happen if they did it.
Your question is extremely odd. The US wanted to do exactly what it ended up doing when Japan gave it unconditional surrender: it wanted to occupy the country and turn it into an ally. That meant rebuilding it, that meant making it a stable democracy, that meant basically eliminating the forces of militarism that gave rise to the Japanese empire. It also meant preventing Communists from taking power. It also meant controlling Japanese media, for example, to make sure that anti-American sentiments did not get a voice. And within a decade it granted it independence again.
That's it. Not genocide. Not totalitarianism. Not colonialism. Not giving it to China. None of those would serve US interests in the long run.
You have to remember that when the US was thinking about what to do with Germany and Japan at the end of World War II, it was very much motivated by a sense that the entire war had been caused by the allies in World War I being pig-headed about Germany, and exacting unnecessary punishments and doing economic damage in a way that ultimately led to the rise of fascism. The US approach after World War II was about avoiding that: turn these countries into future allies, enlist them in creating the kind of world that the US benefited from (non-Communist, free markets, stable democracies, etc.).
The US ended up with full control over the Japanese landmass, military, and government — that's what unconditional surrender meant. It was remarkably successful at turning Japan from an enemy into an ally. None of the things you suggest would have possibly done that — it just would have planted the seeds for future problems.