Is Hakone worth an overnight?
Yes, if onsen, ryokan rhythm and slower mountain air matter. Hakone is less convincing as a frantic scavenger hunt of transport passes, ropeways and photo stops.
Answer
Hakone’s best version is not rushed. The point is often the pause: arriving, checking into a ryokan, bathing, eating slowly, walking through forest or lake air and letting the trip change tempo before the next city. A day trip can give you a taste, especially from Tokyo, but it often becomes a choreography of trains, buses, queues and weather hopes. Stay overnight if you want the onsen-and-ryokan experience to feel like part of the trip rather than a checkbox. Skip the night if your budget is tight and you are mainly chasing a Fuji view, which may or may not appear.