Jacqueline de Signore (ジャクリーヌ•ド•シニョレー Jakurīnu do Shinyorē) is the wife of the current Superintendent-General of the Sauville Police. She shares a past with Grevil de Blois, who turns out to be the latter's childhood friend and crush.
Before her engagement to Superintendent-General Signore, she was framed for the murder of a veterinarian and this causes Grevil to resort to asking help to his younger sister Victorique, for an unusual price.
Jacqueline is a woman with chocolate brown hair and brown pupils. She styles her hair into bun, and leaves a lock of hair hanging from both sides of her face. She wears a light brown coat over a pink undershirt and wears a pleated skirt with a slightly darker color.
Despite being an adult, Jacqueline usually acts much younger for her age, bubbly and always in high spirits. She usually suffers from having a short attention span, and can be stubborn, a constant test to her maid Marion's patience.
However, Grevil knows that she also experiences moments of sadness, which Jacqueline often tries to hide by resorting to impulse buying and trying to act funny at the wrong moments.
She met Grevil as a young girl who does not focus of making herself beautiful for others. She would later see Grevil occasionally, and eventually they began to talk to each other. The two later become friends, although unbeknownst to her, Grevil is starting to fall in love with her.
Years after their first meeting, Jacqueline is engaged to be married to Signore, and after the death of her pet squirrel Q-chan, she is accused of murdering the veterinarian who checked up on her pet squirrel. The accusations against her have saddened her, especially with people's prejudice worsening the situation.
However, to her surprise, she finds herself cleared of all the charges against her, and the suspect surrenders itself to the police... an unexpected resolution which still puzzles her and her husband to this day.
Jacqueline's Helping Hand
After Kazuya Kujo helps in the investigation of an illegal auction in the Jeantan Department Store, he discovers that someone familiar to Grevil has helped the impoverished boy Luigi by helping him return to school. The woman, introducing herself as Jacqueline, becomes friends with Kazuya.
The Trip Down Memory Lane
Jacqueline, with Marion to accompany her, returns to Saint Marguerite to donate a collection of books to the school's library. A short stroll on the town before heading to Saint Marguerite complicates things, however, when Marion loses the collection of books in an incident that switches the books with a box of cosmetics.
They travel to Saint Marguerite oblivious to the switch, and after a reuniting with Kazuya, who had seen her in Saubrème, they head to the library, where they discover Victorique de Blois. It is there that they find out that Marion has picked up the wrong box, and before reporting the incident to the authorities, Jacqueline retells her experience involving her with the death of a veterinarian.
While Victorique fills in Kazuya on the details of the case, Jacqueline manages to retrieve the books on the local police station, which eventually ends up in the hands of Grevil.
Jacqueline failed to see Grevil in the end, but decides to write a letter to him instead, sending her regards to the friend that she haven't seen in a long time.
Challenges in the Inevitable War
Jacqueline continues to support Luigi's education, even through the course of the war; however, it is uncertain whether it was Jacqueline who adopted Luigi into a well-to-do family.
At the early years of the war, Kazuya is running away from a group of men who work for the king, and he eventually reached the Signore residence through Luigi's help. Later on, Jacqueline's husband was confronted by Grevil concerning Kazuya's custody and, thinking that he will ensure Kazuya's safety, allows him to take Kujo. Jacqueline later discovers that Grevil is working for the Ministry of the Occult, and this causes Jacqueline to lose her trust to Grevil.
In spite of what Grevil did, Jacqueline eventually learned to forgive Grevil, and even helped the known son of the Ministry's leader in returning to his job as a detective.
- "Now that I've gotten to this age, I finally understand that. Just goes to show that the passage of time and becoming an adult isn't all bad. Even though back then, I wanted to stay a child forever..." — in Episode 11, while reminiscing to her moments with Grevil