Japan undoubtedly a develop country but the format and the structure of the country is like you have to work to survive. That is Japanese people have lot of job opportunities for them. After graduation they get easily a job and who are not interested in education they do part time job which is also available. But if you are not joining any work in Japan you are not going to have any way to feed your meter.
You have to do work if you want to survive in Japan because the living cost is too high here. If you want to rent a single room in that case you have to pay near about 50,000 Japanese yen without gas and electricity bill. So think how much money you need to earn if you want to have a single room in Japan.
Now it's about food cost omgs food is also expensive in Japan, if you buy a simple water bottle you have to pay 120 japanese yen and in case of juice the price is same and now think about the rest of the food cost by yourself.
Each and everything is expensive here but a good site is they also assure the quality of products such a way.
So now come to the point why I told, the format and the structure of the country is like you have to work to survive.
Simply think if you need to expense more than 1,00,000 yen for one person for survival in japan so how many hours he/she should work? It's the simple calculation that Japanese people work for long time for their better living and they are bound to do it, except it it would be quite difficult for them to survive in Japan.
It's becoming their habit to do work for long time because their is no alter way. It's kind of structure in Japan is to do hard work and work for long time .Japanese people are used to do this from their very young age.