Originally Posted by Kiwi Flyer

There are no flights between Asia and South America. The only options are to route through Australia/NZ, or through North America. Going via North America is not an option for you because you began your itinerary in North America (once you return to the continent of origin you cannot travel to another continent), with one exception. There is a flight from Tokyo to Sao Paulo on Japan Airlines. If you can find availability on that flight all the way through then technically you are not travelling via North America.