Sapporo - Tokyo - Kyoto - Osaka

Hi there,

You can do Nara as Half-a-day-trip if you leave early. Get on the train at 6-7 am to have most of the day for sightseeing.

Hiroshima can also be done as a full day trip from Osaka but Nagasaki is simply too far away. You'd have to spend 1-2 nights in Nagasaki for the travel time to be worth it. Still Hiroshima has plenty to offer for a day. Visit the peace memorial museum and park, then head to Miyajima to see the famous tori gate floating on the water.

Hope this helps,
Daniel