Many people would point to the Bushido culture when it comes to the aura of honor surrounding suicide. However, I think it may go even deeper.
From what I understand, Japan has never been a fully self-sufficient economy. The peasantry were always under some feudal rule and a lack of resources had been the norm. Tragic practises like carrying the elderly into the woods to be abandoned and die were not uncommon. The elderly knew when they had become more of a liability than an asset to the family and graciously accepted their fate.
[0] http://en.wikipedia.org/wiki/Ubasute
[1] http://en.wikipedia.org/wiki/The_Ballad_of_Narayama_(1958_fi...
As I understand it, the Samurai live by the 7 virtues: - Rectitude - Courage - Benevolence - Respect - Honesty - Honour - Loyalty
I wouldn't be surprised if these virtues continue to play a huge role in today's society. That said, I'm also not sure how serious people live by these virtues.