[4] In response to these incidents, MLIT has decided to require railroad operators to install security cameras in all new trains.

[5] The attack began as Hattori, dressed as Joker, reportedly sprayed pesticide into the eyes of the man sitting next to him on the train, before stabbing him in the chest.

He allegedly told officers that he wanted to die after having work problems in June 2021 and that he was no longer getting along with his friends.

[6] Several media outlets noted that the man was dressed in clothing that appeared similar to that of the Joker character from the Batman franchise.

[11] Hattori was facing an internal transfer due to a workplace issue, and was having negative thoughts after learning that his ex-girlfriend whom he lived with till autumn of 2020, the year before he committed his act, was getting married.