Japan is a country of longevity. Many elderly people live actively. They go everywhere with their friends and some of them go for a trip a foreign country.
In my opinion,
1) First of all most Japanese people originally lived a very humble lifestyle before modern economic development , after World War Ⅱ. They would have eaten only simple Japanese food, fish and vegetables when they were young. Moreover, they didn't eat much and they ate only natural ingredients, vegetables that were grown with no agricultural chemicals.
2) Secondly, medical treatment is developing day by day. For a long time serious diseases weren't curable. However, even cancer is a disease that isn't fatal now if we can find it early enough. The improvement of treatment is remarkable. So elderly people can live longer.
On the other hand, the number of aged people that die alone is increasing now. Recently many aged people , especially in big city, live alone with no family or children live in other home. This situation is a problem for our society. I have heard a news that a aged man died without being known his death by neighborhood.
Living longer is excellent, however, it is best to live longer with good health and a reliable family or friends.