Ninzaburo Shiratori/Relationships

Sumiko Kobayashi
After learning that Sumiko is his first love, through an investigation with the Detective Boys where he himself solved the crime, Shiratori has been frequently phoning her and visiting her at the elementary school under the guise of warning her of dangerous activity in the area. He has also resigned from his "position" as Chief Executive of Miwako Sato's Line of Defense, telling the other officers to let Takagi and Sato be.

During the investigation of the Loan Shark Murder Case, Sumiko is brought to the police station as a witness and learns that she resembles Sato, and that Shiratori used to be in love with her (Sato). This upsets her, thinking that Shiratori is affectionate of her only because she resembles Sato, and she behaves coldly and harshly towards Shiratori, even claiming to not remember their first meeting when he tries to confess his feelings to her (she remembers the incident, but perhaps she doesn't believe that Shiratori is the same person), saying that it must have been Sato he met instead. However, after saving her from the culprit, Shiratori recites the provisions of the Japanese Law - just like he had done in the book store years ago - to quash the murderer's justification of his actions, causing Sumiko to remember him as the same person. Finally, Shiratori confesses his true feelings to Sumiko, and the two of them begin dating. Sumiko would often often present home-made bentos to Shiratori.

Miwako Sato
Shiratori used to show affection for Miwako Sato, whom he believed to be his first love interest from his childhood days. He would often ask her out on dinner dates but always end up being turned down, much to his dismay. He also knows that Takagi also has feelings for Sato, and often will put down Takagi while in front of her, by showing off how he is wealthy and wants to take her to fancy dinner dates. However, Sato does not feel the same way for him, and always turns him down. In later episodes, Shiratori is the leader of a police force that is mostly hellbent on getting Takagi and Sato to break up, especially when Sato and Takagi begin to move further in their relationship. Shiratori once even tries to sabotage a date at Tropical Land that Sato and Takagi are having, have the police lie to Megure that they are working, so that they can secretly pretend to be staff members of Tropical Land, and try to ruin the date.

In another situation, Shiratori almost marries Sato, through an arranged marriage set up by Shiratori's family and Sato's mother. However, thanks to an ultimatum set up by Sato, Takagi is about to stop the marriage, with the help of Conan and Dr. Araide, before Sato and Shiratori can kiss.

Shiratori's strong infatuation for Sato came from a childhood memory of his first love who looked remarkably like her. However, after solving a case with the Detective Boys, he meets his actual true love: Sumiko Kobayashi. Since then, Shiratori has become a friend towards Sato and fully supports her relationship with Wataru Takagi.

Juzo Megure
Megure and Shiratori share a fairly close relationship, and the later is frequently seen assisting Megure in investigations. The bond between them is evident in Movie 2:The Fourteenth Target, where Shiratori helps an injured Megure in swimming and escaping the flood, after the underwater restaurant they were in, is made to collapse by the murderer.