Akiko Sayama (Chieko Honda) is the hidden villainess of "Night Baron Murder Case", episodes 3.14, 3.15, and 3.16 of Case Closed (airdates July 21, July 28, and August 4, 1997). She was a high school math teacher and the fiancee of karate champion Satoru Maeda. Akiko and Satoru were of a group of people attending a mystery tour at the Izu Princess Hotel.
Akiko's backstory revealed that she had history with fellow tour attendee, Tokio Ebara. Three years prior, Tokio hacked into the records for the company Akiko's brother ran, stealing a firewall program that he had put all his money into creating. The theft drove Akiko's brother to suicide, and years later, Akiko orchestrated the mystery tour as a way of luring him into her vengeful clutches.
To lure Tokio to the contest, Akiko claimed that the winner would receive the "Night Baron" virus, a legendary virus that was capable of hacking into any computer system. When she saw that detective Kogoro Mouri had arrived in place of Professor Hiroshi Agasa, the evil Akiko tossed Conan Edogawa over a hotel balcony into the pool below as an attempt to scare Kogoro away. Akiko then used Tokio's perverted lust for her to seduce him into coming to her hotel room, claiming she would give him the virus. There, Akiko drugged Tokio with sleeping pills and planted the Night Baron's glove on the balcony of Tokio's room before dressing him as the Night Baron and throwing his body from her balcony, causing him to get impaled on a statue.
Akiko's intention was to make Tokio appear to be the organizer of the tour and that his death was the result of him slipping and falling while trying to cause mischief. When Satoru realized from the way she tied Tokio's tie that Akiko was the killer, he stole the Night Baron costume and appeared before Akiko and Ran Mouri in the elevator to give Akiko an alibi out of love for her. But Conan was able to deduce Akiko as the real killer from the fact that the wind would've blown Tokio's body to another location. Satoru attempted to take the blame for Tokio's murder, but Akiko stopped her fiancee and boldly confessed to killing Tokio, revealing how he had driven her brother to suicide and stating that Tokio deserved to die. Before she was arrested, the evil Akiko teased Satoru for proposing to her, cackling as she was handcuffed by the police. But as Akiko was taken away, she was surprised to hear Satoru tell her that he still loved her and would wait for her while she was in prison.
- In the English dub, Akiko's name is translated as Audra Kelly and is voiced by Cynthia Cranz.
- Chieko Honda also voiced the evil Tom Cat from Violence Jack.