Yamanashi is a small city in the Kōfu Basin, northeast of Kōfu and within easy reach of Tokyo by train. It is not the same thing as Yamanashi Prefecture, but it gives a good taste of the prefecture's fruit-growing identity: orchards, grapes, peaches, hot days, and mountain views.
The city earns its place because its sights are varied for its size. Seihakuji has a National Treasure Buddhist hall, Nezu Memorial Museum preserves a wealthy merchant's house and gardens, and Fuefukigawa Fruit Park looks across the basin toward the night lights and, on clear days, the mountains beyond.
Yamanashi is best treated as a gentle half-day or day stop from Kōfu, Katsunuma, or the wider Mount Fuji side of central Honshu. Come in fruit season if you can; the city makes most sense when the orchards are part of the day.