Daichi Mizushima is a young man who has locked himself up in his room after his father's death. He and his sister, Ayaka believe that the company their father worked at, had stressed him out, and she confronts Makoto Shinoda about her suspicions, but Makoto says that no one is allowed to stay after hours at the company. Makoto believes it was Daichi's fault, for being a 'hikikomori', one who locks himself away from the outside, but Ayaka doesn't think so and orders him to leave.
In the Twilight, Ai plays with a string figure, when she receives Daichi's request, wanting to send Makoto to hell. Ai meets with Daichi, who is surprised to see her, and she gives him the black straw doll. She also gives Daichi her warning of him also going to hell once he dies, that is if he wants to send Makoto to hell.
At Makoto's company, both Ren and Hone Onna are disguised as office workers, though Makoto seems to have his eyes on Hone Onna. The two share what they know about Makoto explaining that he took charge of everything, once he became manager. Back at the Mizushimas', Daichi has a memory of his dad asking to come out of his room, but Daichi ignores him, much to his dad's disbelief and is heartbroken. Mr. Mizushima continues to ask Daichi to come out of his room, but he refuses by listening to loud music or being on the computer. In the last flashback, Daichi hears his sister crying that their father committed suicide, and he deeply regretted that he didn't see his father's face that one time.
Daichi decides to do some detective work, starting at the Manga cafe, where the owner explains that Mr. Mizushima would stay at a computer throughout the night till closing, and Daichi is given a CD, which contains some evidence that Makoto had overworked Mr. Mizushima. Ayaka goes to visit Makoto and tells him what she knows from the CD Daichi found, also pointing out that Makoto had overworked several employees in the past, causing some resignations, but Makoto is not satisfied. Back home, Daichi finds his father's computer diary, and he discovers that Makoto had Mr. Mizushima work overtime, much to the limit, and to the point of humiliation. He also finds that his father loved him and Ayaka, even when he wasn't there. Back in the present, Ayaka is attacked by Makoto's men and they take the CD, leaving Ayaka, bleeding on the sidewalk.
At the hospital, a policeman tells Daichi that according to a witness, Ayaka was pushed down the stairs by the two thugs. Daichi realizes that the CD is gone and decides to confront Makoto on his own, taking the black straw doll. Daichi asks why did Makoto overworked his father, but Makoto pushes him to the ground, saying that people like Mr. Mizushima were the reason of Japan's slow economy, almost bankrupting Makoto's company. After Makoto threatens Daichi about his sister, Daichi decides to do what is necessary and pulls the string.
Makoto finds himself back at his office and is confused. Upon entering one room, he finds Mr. Mizushima, alive, and typing away on a computer. Then, Mizushima turns his head a full 90 degree angle and Makoto runs out of the room, only to find that Mizushima has hanged himself from a shaft. Makoto goes to run, but a rope goes around his neck and he is hanged from the shaft. Ren, Wanyuudou, and Hone Onna appear, telling Makoto to apologize to Daichi and his father, but Makoto refuses, saying that he cleaned Japan's economy. Then, Ai appears and delivers her famous line, therefore, teleporting Makoto to her ferryboat. On the way to hell, Ai tells Makoto that she will give him endless work, with no rest, just like he did with Mizushima.
Back at the Mizushimas', Daichi pulls down the cardboard he had on his windows and the sunlight fills the room for the first time in years. Daichi then sees the black fire symbol on his chest in the reflection and hears Ayaka call for him and he goes to school.