The smell of mold wafted through the small underground room at a municipal-run cemetery in the city of Saitama in late November, where around 600 unclaimed urns filled the shelves.

Pointing at the only vacant rack in the vault, Saitama official Satoru Shimizu said it won't be long before it runs out of space, as unclaimed remains have been on the rise in recent years.

"It's OK for now, but it will eventually be full," said Shimizu, an assistant manager in the life and welfare division of the Saitama Municipal Government. "It's a bit sad to think this bleak place is the final destination" for some people.