Without sakoku, Japan may never need a Perry expedition

What changes if Tokugawa Japan never adopts its policy of isolation?

Continuous European trade could remove the need for Perry's expedition and give United States-Japan relations a very different beginning.

The counterfactual depends on continuing trade rather than a sudden nineteenth-century opening. Sustained contact with Dutch, British, and French merchants would give Japan different external networks and a longer path of adaptation to European commerce. Under those conditions there may be no need for Matthew Perry's expedition to force access. Removing that confrontation changes the starting point of United States-Japan relations, without implying a single inevitable later outcome.