My itienary

Hi there,
I will visit japan in june. The total person is 3 adult n 1 baby. My flight from hk will arrive in tokyo and i will stay in tokyo for 2 days. The first day just stroll around neghvourhood in hotel and 2nd day to disneyland. While for the 3 -8 day i will visit osaka stay for 5 day and 2 day in kobe. What jr pass should we buy ? Meaning the most efficient since we are only exploring most area where my baby can play. Do you think i still need jr pass 7 day ? Or i need to buy 1 one trip to osaka and combine with jr west or anything else ? My flight to hk will depart from osaka.