21days in Japan

Hi guys,

I'm struggling to fully understand how JRpass works.
So far my itinerary will be:

Arrive in Tokyo - Matsushima - Sendai - Hachinohe - Hakodate - Sapporo,
then I will go down from Sapporo - Osaka - Kobe - Nara - Kyoto - Tokyo

My question is, if i take the 21days JRpass ($748), will it cover all my transportation expenses without having to spend anymore money on top of what I've paid?

Thanks! This would be my first time to go to Japan, so excited but really confusing!