Do I need a JR pass?

Hi guys
Do I need a JR pass or is it not worth it?
family of 5 starting at
Tokyo 5 nights
Mt fuji 3 nights
Kyoto 3 nights
Osaka 5. nights
Day trip to Hiroshima
back to Tokyo 6 nights

I assume we will also have to use trains that are not included in the JR pass.
I have been told by different people that 'yes' get it and 'no' it's not worth it.
I'm so lost, especially given the cost of the pass and the fact that there are 5 of us!
Please help
TIA