Going to Japan for 21 days - what is my best option?

Hi There!

My partner and I will be going to Japan from 7th November-28th November. Can I check my itinery and ask what rail pass would be best?

Nov 7-13 - Tokyo
Nov 14 - Mt Fuji (and stay 1 night at Mt Fuji)
Nov 15 - Stay in Tsumago
Nov 16 - 22 - Kyoto
Nov 23 - 28 - Osaka

I was wondering if it would be most cost-effective to begin a 14-day rail pass on November 14th, when we are planning to go from Tokyo to Mt Fuji. This would be instead of getting a 21 day rail pass for the whole trip, as we aren't planning on doing any day trips outside of Tokyo for the first seven days.

Can you let me know what you think the best options would be?

Thank you!