People have a habit of vanishing in Japan---even hundreds of years ago, it happened often enough that myths were created to explain these sudden disappearances. 神隠し (kamikakushi)--to be hidden by the gods. Even now, every year over 80,000 people are reported missing. And that may be the tip of the iceberg--because only family members can make those reports. If your girlfriend, high-school buddy, co-worker just evaporates one day--you can go to the police but unless you can prove foul play, they may not even open a file on the case.

Japan Subculture Research Center