So from what I understand when it comes to why many elderly are still working, it is a bit multifaceted. My grandpa for instance still works not because he needs to but because he has his own business, and it keeps him in good mental and physical health. I've met elderly people that are either in a similar camp, or choose to continue doing so because it keeps them active. Another reason outside of having to because of depleted savings, is because the Japanese workforce needs them to fill the gaps of not having enough young people to do the more mundane, low level, laborious jobs. This is why you see many elderly filling in for low skilled jobs such as cashiers at convenience stores (also being filled by foreigners), waiters and waitresses, and often you'll see many of them working at airports as janitors or general airport staff. And like you alluded to there is a cultural element, in that in Japan contrary to say the States, there isn't as much of a desire to retire and essentially do nothing, the Japanese prefer to stay busy bodied and continue to provide value in some way to their economy and society at large. Obviously there are moments I feel for some of these elderly people especially if it's financial circumstances that bind them to such obligations, but I've also met just as many elderly who work because they enjoy it, and often I've noticed the elderly are much more enthusiastic when working in comparison to the younger generation. For instance, at an udon restaurant I went to in Tokyo, the waiter serving me was an older gentleman but was full of so much pep and we ended up talking quite a lot, and he clearly livened up the restaurant.