itinerary question

Hello! I will be visiting Japan in September with my son. We plan to take the following itinerary :
Arrive in Tokyo on 1st September
On the 3rd day of September off to Hakone via Kamakura and Enoshima (if possible)
Spend the night in a ryokan in Hakone.
On the 4th day of September off to Kyoto.
Spend the next 4 days in Kyoto and plan a day trip in Hiroshima another in Himeji.
On the 8th of September take on a shinkansen ride to Tokyo Narita for our return.

Would yoy recommend a JR pass? Is it the most affordable option?

Thank you in advance!
Vicky from Athens, Greece.