An English teacher named Seiji Hasumi (Hideaki Itō) is loved by his students and respected by his peers. He graduates from Harvard University with an MBA, and works at Morgenstern, a European investment bank, for two years. Hasumi returns to Japan to pursue high school teaching. However, his outward charm masks his true nature. In reality, Hasumi is a Psychopathy#Sociopathy who is unable to feel empathy for other human beings. Specifically, he has a severe antisocial personality disorder. Having killed both of his parents and his former tutor at the age of fourteen, Hasumi turns into a fiendishly clever killer. During his time in the States, Hasumi meets a partner in crime, an American named Dave, who thinks he shares the same "hobby" as Hasumi – killing people for fun. The two can be seen carrying buckets full of human blood, bones, and organs somewhere, giving off the notion that they committed numerous murders while working together. Hasumi eventually kills his partner by knocking him out and burning him alive inside a barrel, stating that while Dave enjoys killing for fun, Hasumi does not.