Masumi Hayashi (林 眞須美, Hayashi Masumi, born July 22, 1961) is a Japanese mass murderer convicted of putting poison in a pot of curry being served at a 1998 summer festival in the Sonobe district of Wakayama, Wakayama, Japan.
A communal pot of curry being served to residents of Sonobe district, Wakayama, was poisoned with at least 130 grams of arsenic – enough to kill over 100 people – on July 25, 1998.
[1] Attention quickly focused on 37-year-old mother of four Masumi Hayashi as a witness had seen her at the curry pot, and she had easy access to arsenic because her husband was an insect exterminator.
Hayashi has also been tried for three other attempted murders by poison that had occurred during the previous 10 years, with the motive in those cases being life-insurance benefits.
The main feature of this case is that the defendant Masumi Hayashi's motive for committing the crime has not been clarified and there is no direct evidence.