Hi, I am planning to take a trip around Kyushu area, then back to Narita airport. Itinerary as follows:
Day 1-2 Miyazaki
Day 3-4 Kumamoto
Day 5-6 Osaka
Day 7 - Narita
Please suggest what type of JR pass I should buy?
After I purchase the JR pass, can I start making seat reservation online prior to my travel dates? Please confirm. Thanks a lot.

