Trip duration was 10 days with the last day being wasted for our flight back.
We rented a car for the whole trip and my brother stays in Tokyo so the itinerary might look a bit hardcore but it was something like:

Day 01 - Arrive Narita early in the morning, straight to Nikko for the shrines etc
Day 02 - Went up to Okunikko and visited Chuzenjiko, Sainoko, Senjogahara etc
Day 03 - Went back down to Nikko and stopped by Kegon Falls before proceeding to Kirifuri, spent the night at Yunishigawa Onsen
Day 04 - Nasushiobara & Kinugawa Onsen then back to Tokyo for the night
Day 05 - Stopped by Otsuki to see Saruhashi on the way to Fuji Five Lakes, Oshino Hakkai, Fuji Sengen Jinja Shrine then Yamanakako for the Yuyake no Nagisa festival
Day 06 - Mt Fuji from Chureito Pagoda then headed off to Kofu to visit Shosenkyo, finished off the night at Kawaguchiko's maple corridor for the Momiji Matsuri Festival
Day 07 - Funatsu Tainai Lava tree molds before leaving Fuji Five Lakes back to Tokyo, Shibuya at night
Day 08 - Shibuya/Harajuku/Shinjuku
Day 09 - Asakusa & Akihabara
Day 10 - Sayonara