DELHI-OSAKA-DELHI Trip

Dear

We are 2 senior citizens and 2 grown up children (19 & 11) travelling to Japan for the first time and going to stay for 10 days from 1st June to 11 June 2025. We have planned to visit tourist places in and around 200 kms of OSAKA & KYOTO during this trip. One day we have planned for TOKYO visit i.e. same day return. Please let me know if buying JR Pass would be a good idea for entire trip or for a week. Also if we buy for a week, then will be cheaper to buy Online now or we can buy at same price as we land in Japan? Please suggest!