It occurred on June 9, 2010 when Sanae Shimomura, a 23-year-old Japanese single mother in Osaka, sealed the door of her apartment shut, abandoning 3-year-old daughter Sakurako Hagi and 1-year-old son Kaede Hagi inside.
Since Shimomura did not come to work for several days, a colleague went to her place and noticed a strange smell beyond the door.
[1] Social workers had attempted to stop by the apartment several times over the course of the children's confinement, but never found anyone home.
The apartment was in a lively, populated area, but nobody knew that the children were confined.
[1] She was reported to have wanted free time for herself and was quoted as saying that she had grown "tired of feeding and bathing" her two children.