Request for information

Dear all,
I would kindly request your assistance on purchasing the JRPass.
I will travel to Japan with my two kids (21 and 16 years old).
We arrive to Tokyo on the 27/07.
30/07 we go to Mont Fuji lake zone in Fujikawaguchiko,
31/07 we travel to Kyoto
3/08 we travel to Takayama in Alpes
7/08 we return to Tokyo for last night before the departure to Belgium.

Would you kindly indicate is it cheaper to purchase three JR passes or rather get separate tickets for the above mentioned travels please?

Thank you very much for your assistance and recommendation

Best Regards
Monika