The mound serves as a communal grave, with multiple unrelated people buried together. It is treated as a perpetual resting place, with the cemetery responsible for its long-term maintenance and a partner shrine continuing rituals indefinitely — a feature Marumo says is a key selling point. The price starts from 183,000 yen, and unlike conventional graves, which can cost between 5,000 and 20,000 yen annually to maintain, there are no ongoing management fees. Kawamura, 69, who purchased a space after his wife passed away last year, said the concept appealed to him. "I can be buried with my wife, and there's no annual maintenance fee to worry about," he said. The project has also given rise to an unusual new tradition: "kofun reunions" for people who have purchased plots in the same burial mound while they are still alive. Kawamura, who attended one such gathering, recalled meeting a fellow future neighbor whose husband had recently passed away. "We joked about becoming neighbors. It's interesting to be able to share a smile while we're still alive," he said.