From a game theory perspective, you'd start out with the most military sensitive items first. If Japan retaliates, you slowly broaden the embargo to exert pressure.
But I'm also not particularly clued in about what this is in response to. If this is strictly about Japan's recent comments over exploring nuclear weapons, then there's a couple ways this can go.
1. You start out slow and widen the scope of the embargo with time (or in response to Japan's retaliation) until Japan gets the hint.
2. You start out with a bazooka and go for major economic damage to force Japan to either rescind their comments, or to come to the bargaining table.
On the other hand, if this is more about Japan's political direction in general... I don't really see how this ends quickly. Japan is firmly married to America's security umbrella and I don't see them getting rid of Takaichi quickly. Though if there is someone who knows a lot about Japan's politics, feel free to correct me.
Which means that this might be a long and prolonger trade war that's going to be damaging to both countries. The impact to Japan's downstream industries will be significant. Chinese suppliers tho, will also feel the pain. China is also a major importer of Japan's goods. Other than the obvious high-value SEM inputs China buys from Japan, there's plenty of machinery, electronics, medical equipment, etc. Domestic industries can probably fill in gaps, but there's still pain from switching suppliers, possible quality/yield drops. There's probably a few critical irreplaceable inputs as well. $300 Billion USD in trade volume between two neighbors is at stake.
What do you all think? Is this going to quickly escalate...? Or is Japan going to back down?