Do we need JR Pass?

Hi, we are family of 5. We plan to go to Japan this Dec. Our Itenerary is as follow:
26 Dec: Arrive at Kansai airport. Stay in Osaka
27 Dec: Stay in Osaka. Universal Studio
28 Dec: Stay in Osaka. Day tour from Osaka to Nara
29 Dec: Travel from Osaka to Tokyo
30 Dec: Travel from Tokyo to Hakone. Stay in Hakone
31 Dec: Travel from Hakone to Tokyo. Stay in Tokyo
1 Jan: Day trip Tokyo to Kawagoe. Stay in Tokyo
2 Jan: Travel from Tokyo to Sapporo (by airplane). Stay in Sapporo. Plan to visit: Hokkaido Shrine, Odori Park.
3 Jan: Sapporo: Noboribetsu Hot Spring
4 Jan: Sapporo: Exploring city (Government building, Sapporo clock tower)
5 Jan: Travel from Sapporo to Seoul.

Do we need to buy JR (how many days), or regional pass or just simply using suica?

Thank you so much :-)