Villainous blackmailer Motoka Aida
Motoka Aida (Yukari Honma) was a villainess from "The Strange Family's Request", episodes 14.09 and 14.10 of Case Closed (airdates May 16 and 23, 2005). She was a wedding planner and the fiancee of Eisuke Kariya, who was found bludgeoned to death and stabbed in a telephone booth twelve years prior to the episode's events.
Eisuke was believed to have killed Motoka, and had gone missing afterwards. The episode's progression revealed that, on the night of Motoka's death, she and Eisuke called Daisaku Kariya (Eisuke's father) from the phone booth to ask if Motoka could spend the night at their house due to her missing her train home. In response, however, Daisaku revealed to Motoka that he knew she had been unfaithful to Eisuke and ranted that he wouldn't allow her into their family.
In a blind rage, Eisuke attacked and stabbed Motoka, running home and confessing his crime to his brother Shigehide, who agreed to help cover for his brother by hiding him in the attic. But when Shigehide went back to the phone booth to check on Motoka, he found she was injured, but alive and stable. But as Shigehide prepared to take her to the hospital, Motoka asked him if he was going to "take responsibility" for what happened. It was then that Shigehide was revealed as Motoka's lover, as he believed she was talking about marrying her. But in response, the evil Motoka turned heel and revealed her intentions to use her knowledge of Eisuke's attack on her to blackmail Shigehide, while revealing that she'd only planned to marry him or Eisuke for their family's wealth. In response, Shigehide killed Motoka by bludgeoning her to death, hiding Eisuke in the years following and allowing him to be blamed for his fiancee's murder.