Rio Sanada, the CEO of Sanada Wellness, is a spirited businesswoman who was chosen as one of the “Global Top 100 Influential People in Their 30s.” After fifteen years, she reunites with someone who she had a close bond with: Daiki Miyazaki. Daiki is now a detective, and Rio is an important witness to a murder case. The story goes back to fifteen years ago, Gifu Prefecture, 2006. Rio is a high school senior hoping to study medicine in college. Her father, Tatsuo Asamiya, was busy working as a college dorm supervisor, thus Rio watched after her little brother Yu. At the time, Rio had a crush on the college track team’s ace athlete. Then, one night, an incident occurred at the dorm while Tatsuo was away. Azusa Sanada, who was worried about Rio, sent a lawyer by the name of Kenichiro Kase.

Rio and Daiki unexpectedly reunite after fifteen years. Daiki asks Rio to come in for questioning. He asks about her relationship with Akira Watanabe, who was found dead, and also asks about items Kosuke left behind after his death. Rio returns to her company, where the executive director shows her a photo that he received from a freelance journalist. Her worried lawyer, Kase, makes her promise not to meet with the police alone anymore. Meanwhile, Daiki begins investigating the link between this murder case and the missing person case fifteen years ago. The story goes back fourteen years to the year 2007. Rio is having trouble adjusting to life in the Sanada household. There is tension with her older brother, Masanobu, and she is unable to freely contact her little brother Yu.

Daiki tells Rio, he wants to chat as friends, thus they both meet at a restaurant. It is a little awkward, but nostalgia flows between them, and Rio begins talking about what happened that night. Daiki returns to the station and checks Rio’s movements through local security cameras. There are no contradictions with what she said. His partner, Hitomi Kuwata, also feels that Rio is not the culprit, but she is bothered by Daiki’s half-hearted behavior. Meanwhile, Sanada Wellness receives a threatening email. Goto suggests that they cancel the company’s business briefing, but Rio refuses. If analysts and the media approve of this new drug at the briefing, she thought that her little brother Yu, who suddenly disappeared from her life, would come back to her.

In addition to the uproar at the business briefing, articles inciting suspicion toward Sanada Wellness are circulating, causing Goto to criticize Rio even more. Goto is also starting to distrust Shiori, who is snooping around behind the scenes at the company, so he instructs his informant to look into her. Meanwhile, the police are pursuing the trail of a man who handed over five million yen to Akira, the murder victim. Daiki and Kuwata visit Sanada Wellness to ask Rio and Kase if they know this man. He also asks about Kase’s whereabouts the night of the murder. The next morning, an online article calls her medicine a clinical trial drug full of doubts, which prompts uneasy test subjects to stop their clinical trials. Now, even Sanada Group’s stocks are taking a hit.

Rio finally reunites with her younger brother, Yu. He shares what kind of life he has lived these past nine years and reveals his own crimes via his cell phone videos. Meanwhile, the police have found the residence of Earphone Man, or Makoto Ikuta. They have figured out the connection between Makoto and Sanada Wellness, and have determined that Makoto and Yu are one and the same. Also, Daiki visits former track team member Nagashima, who caused a marijuana incident fifteen years ago. Here, Daiki gets valuable testimony about the night of the incident. Meanwhile, Kase is investigating Shiori, who is snooping around for information about Sanada Group, and discovers her connection with Goto. Rio, after talking to Yu for the first time in nine years, does something bold.

Kase visits Yu, who was taken away by the police. Yu confesses that he was the one who murdered not only Akira, but also the victim fifteen years ago. Furthermore, Kase learns that Yu’s struggle with Akira at the park was recorded in his earphone camera and decides to analyze the video data. Meanwhile, Rio is worried about how Yu might be treated and feels uneasy. Kase informs her of the situation Yu is in and kindly comforts her, which helps Rio manage to fall asleep. Goto and her older brother Masanobu want Rio to take responsibility for Yu as CEO, while the video data analysis that Kase ordered from a civilian forensic investigator is finally done. Kase is suspicious about something. Daiki and the police are also gathering evidence to back up Yu’s testimony.