As a child, Shiratori studied diligently to one day become a lawyer, and had even memorized some laws by heart. One day, he witnessed a young girl confronting two juveniles trying to steal mangas from a bookstore. When the two offenders had pushed the girl to the floor for her protests, and seemed about to hurt her, Shiratori had stepped forward to recite the provisions made in the Japanese Law to punish stealing. This somewhat unnerved the juveniles and attracted the attention of the store owner and the other customers, causing the offenders to hastily get away. To thank him for helping her out, the girl bought him a drink and made a sakura petal pattern from the straw wrapper, saying that the sakura was the symbol of courage for the Japanese police _(due to the distinct form of the Japanese police badge),_ and Shiratori had acted with courage just like them. It was because of this incident that Shiratori decided to become a cop rather than a lawyer, and also started to consider the girl to be his childhood love.

Shiratori later joined the Tokyo Metropolian Police Department and worked alongside Inspector Megure, often acting as an extra officer or pair of eyes, though he later became an inspector of his own. When Miwako Sato joined the department, Shiratori believed that he had found his childhood love again, and as a result both he and his younger colleague Takagi considered each other rivals for Sato's affections. Shiratori would often try to show off in front of Takagi by asking Sato on a date, but she always rejected him, much to his dismay.

In pursuit of love, Shiratori has a one track mind and is willing to abuse his police powers to achieve his desire. He even became the leader of a secret police group which protected Miwako Sato from the affections of other police officers like Takagi. Shiratori fixated on Sato because he believed she was the childhood crush who completely changed his life at a chance meeting in a bookstore. Shiratori is crushed when Sato chooses Takagi in the end, and can't truly give up his feelings for her. He later discovers that Sumiko Kobayashi is the true girl from his childhood memories. Once the realization sets in, Shiratori's Sato complex dissolves and he develops an affection for Sumiko that soon blossoms into mutual love. Meeting Sumiko has also helped cure his arrogance to a large degree. Shiratori more than once tried to use his riches to get an edge over Takagi over Sato in the past, but now that he's with Kobayashi he does it solely to make her happy. He's noticeably more friendly towards Conan, Ai and the Detective Boys as time passes.

(Source: Detective Conan World)