My itinerary

Hello all! We (2 of us) are going to Japan in Jan 2018. Below is our itinerary.

9/1 Land Tokyo at 4pm.
10/1 Tokyo
11/1 Tokyo
12/1 Tokyo
13/1 Tokyo
14/1 Mount Fuji
15/1 Mount Fuji back to Tokyo take overnight bus to takayama (if there is any?)
16/1 takayama day trip to shirakawago
17/1 takayama then Kyoto
18/1 kyoto
19/1 kyoto
20/1 Kyoto
21/1 Osaka (if have time, nara day trip)
22/1 Osaka
23/1 Osaka 11pm flight

Is it worth buying JR Pass?
Is there any overnight bus from tokyo to takayama in Jan?

Thanks :)

You could make the JR pass worthwhile, depending on you side trips from the cities that you are staying at, but probably not.

What you are looking for is most likely the Nohi bus line out of Takayama, which has a highway bus to from Takayama to both Tokyo and Kyoto.

https://www.nouhibus.co.jp/english/

I hope this helps. Good luck, in planning your vacation.