Why are you going back and forth? Just go to Karuizawa from Kanazawa. Train fare for one way costs ¥10,920. Then go to Tokyo from Karuizawa.
Calculate your fares via Hyperdia before you commit to a JR Pass. Else consider Hokuriku Arch Pass.
Thanks for your comments, Thwysg. I missed that point out. That would save me much time. I will check out Hokuriku pass too.
Here is the revised iti.
Day 1. Arriving in Osaka morning flight.
Osaka Aquarium, Tempozan Market Place, Takoyaki Museum.
Day 2. USJ.
Day 1&2 : Planning to stay nearby USJ Area.
Day 3. Osaka Castle, Kuromon Market, Dotonbori.
Day 4. Osaka Science Museum, Osaka Museum of House and Living, Umeda Sky Building, Pokemon Centre Osaka, Kids Plaza Osaka.
Day 5. Nara, Shinsaibashi.
Day 6. Kyoto : Fushimi Inari, Kimono Forest, Arashiyama.
Day 3-6 : Planning to stay around Namba (Osaka).
Day 7. Kanazawa. Overnight at Kanazawa.
Day 8. Proceed to Shirakawa-go for half day, then proceed for overnight at Karuizawa.
Day 9. Karuizawa then proceed to Tokyo.
Day 10. Disney Sea.
Day 11. Tokyo (need to look more into this).
Day 12. Tsukiji Outer, Odaiba. Last flight out of Haneda.
Some questions in mind.
1. For Osaka hotel, would it be better to just stay in 1 area i.e. Namba from Day 1 to 6 ? Is this a good base for USJ, Nara, Kyoto trip ?
2. Has anyone been to Shirakawa-Go and Karuizawa around mid Dec ? Has it started snowing ? One of the reasons to included this place is to experience snow.
3. Is 1 day sufficient for Karuizawa?
Thank you.