Stroll the colourful streets of one of the largest Chinatowns in the world — temples, food stalls and souvenir shops make for a lively morning; most shops open ~10:00 but gates and streets are pleasant from early.
Ride the ropeway for views of Mount Fuji and the valley; Owakudani may be closed during high volcanic activity — check the latest status before travel. Ropeway usually runs ~9:00–17:00.
Take the bus to Lake Chuzenji and Kegon Falls; observation platforms and the elevator to the falls are typically open 8:00–17:00 (elevator often JPY550).
Final meal options include airport restaurants or a last local izakaya in Narita — airport eateries are open late and offer a range of Japanese and international dishes.