Okunoin (奥の院) is the world's oldest still-used graveyard. It's located in a cedar forest on a mountain and nature is constantly reclaiming the monuments.
Beautiful. But is it "still used?" I went down a rabbit hole and the only mentions of use other than visiting is people wishing to scatter ashes or place a lock of hair on the grounds.
Well there are a good array of modern corporate memorials like Panasonic. Some of the corporate memorials have pictures of former employees that are added to over time as well.
There are other very shiny newer monuments in parts too but i don't know how old they are. The main path is 2km long, it covers a lot of ground.
I just found Johnny Kitagawa's grave is there. He died 2019, and his ashes were sent to various celebrities but here's the grave. Google translate gives enough info