Consecutive days

Hello, we will be in Japan for 21 days. We will be spending approximately 3 nights per place, Tokyo, Mt fuji, Shimodo, Kyoto, etc and flying home from Osaka. My question is this: will a 7 day pass be the pass to get? Does each day stand alone, in other words can I travel 7 different days within the 21 days on a seven day pass, or does the 7 day pass expire 7 days after I initiate it? Thanks