The drama tells the story of a group of seven university students who travel to a deserted island where a strange decagonal mansion stands. It was the scene of a grisly mass murder six months earlier, and events soon turn ominous.

Yomogida Fujiko is an office worker with an academic complex. She works hard and becomes a full-time employee at an insurance company, but because of her diligence, she is unable to refuse the work she is asked to do and accepts it with a smile on her face. One day, an elite company employee, Nishina Soma, moves into the room next door. Fujiko is soothed by the time she spends with her very kind and gentlemanly neighbor. But why did Nishina, a supposedly elite man, move into this shabby apartment, and why is he so kind to Fujiko...? It seems that Nishina, who does not speak much, is a stranger to Fujiko...?