JR Pass for 18 day itinerary

Hello,
I was hoping you could help me decide whether to buy a JR pass or if regional passes/ individual tickets might be better? As I'll be in Japan for 18 days it falls between the 14 & 21 day passes. This is my itinerary:

Day 1 Natita airport- tokyo
Day 5 tokyo- hakone
Day 6 Hakone - Ito- Yaizu -Kyoto
Day 9 Kyoto- Kanazawa
Day 12 Kanazawa- Naoshima
Day 13 Naoshima- Teshima
Day 14 Naoshima -Takamatsu - Koyasan
Day 16 Koyasan- Osaka
Day 19 Osaka- Osaka Airport

Thank you in advance for your help,
Kind regards,
Aisling