First, the honest part: a day trip to 'Mt Fuji' doesn't mean climbing it — the climb is a July–September overnight effort. What you actually do is go to the lake towns at its foot for the iconic view of the mountain reflected in water. The base for that is Kawaguchiko, and the whole game is timing the weather.
Take the highway bus from Shinjuku (~2 hrs, reserve ahead) or the train via Otsuki. Aim to arrive by mid-morning while the air is clearest.
The north shore gives you Fuji mirrored in the lake. Walk a stretch of the shoreline path rather than staying at one spot; the reflection shifts with the wind.
Climb ~400 steps to the five-storey pagoda framed against Fuji — the single most famous Japan shot there is. In spring it's cherry blossoms; in autumn, red maples.
Several lake-view onsen let you finish the day looking at the mountain from the water. Catch an evening bus back to Shinjuku.
When the mountain actually shows itself, month by month.
See the timing guideYes — for the views, not the climb. Head to Kawaguchiko (~2 hrs) for lake reflections and the Chureito Pagoda. The actual climb is an overnight, July–September only.
The highway bus from Shinjuku to Kawaguchiko (~2 hrs) is simplest and direct; reserve ahead. Trains via Otsuki also work.
Clear mornings from late autumn to winter are most reliable. Summer haze often hides it; afternoons tend to cloud over the summit year-round.