Worth to purchase JR Pass or not?

Good evening, I am writing to enquire whether it is worth it to purchase the JR pass for my holiday in Japan this coming December. Total pax travelling will be 5 pax, from 16 Dec 2019 to 23 Dec 2019. We are unsure as to whether to purchase the 7 day JR pass or not. The itinerary goes as follows: Narita Airport-Nagano-Toyama-Tokyo-Narita Airport. All 5 pax will arrive back to Tokyo on 20Dec, and only 3 out of the 5 pax will be heading back to Narita Airport on the 23rd Dec. Pls advice as to whether we should make the purchase or not. Thank you.

Yours Sincerely,
Mr Ang