Silver Heart's granddaughter (though not by blood). She has striking yellow twin-tails, diamond-shaped hairpins, and unique diamond-shaped pupils. She has a feisty yet occasionally sweet personality. Silver Heart took her in from her burning royal palace when she was just a baby. Since then, she has grown up receiving an abundance of love from him. Her weapons are playing cards and a diamond sword that can cut through anything. She loves strawberry cake. When she was once deceived by Professor Clover's tricks, Guest cleared up the misunderstanding and brought her back. She is still a minor. While she bickers with Spade and Guest, they are like family to each other. She has an assistant named Roko (Hosshi/Scon). He is a talking dog with the ability to bark loudly enough to temporarily deafen opponents. Roko loves corn, is very kind, and speaks politely to everyone, including Queen.

The last disciple to join Silver Heart's tutelage. With his long blue hair and refined features, he is often mistaken for a girl, though his strong masculine charm usually prevents such confusion. He is relaxed, calm, sly, and kind. He lives on his airship, the Twin Thunder Shark. His weapons are playing cards and an Ice Gun—a pistol that fires ice to freeze people or objects instead of bullets. He has a bickering relationship with Guest as rivals. When he gets overly excited, he tends to run a fever and stumble. He is still a minor. While he bickers with Queen and Guest, they are like family to each other. He has an assistant named Dark Eye. She wears bandages over her face and a full suit, and because she uses a deep voice, everyone assumed she was a man... but she is actually a woman. She is calm, kind, and supports Spade excellently. She has a gentle personality.

The mentor to Guest, Spade, and Queen. He is essentially a grandfather figure to them. He took in and raised the three of them after they lost their parents. He was once a legendary phantom thief, but currently, he rarely goes on missions due to back issues. He loves cream stew. He has a playful and kind personality. He is blind in one eye, which he reportedly injured during a confrontation with Professor Clover in his youth. He adores his disciples. He has long, flowing white hair. (He might have been quite handsome in his younger days?)

A phantom thief who wears almost the same outfit as Guest. He wears a purple suit, a black cape, a purple silk hat, and has cyan hair with cat-like yellow eyes. He is often called a 'chunibyo.' According to Rose, he once drank a whole cup of black coffee after watching a cartoon when he was little... He has a prickly personality, though he is occasionally kind. Because Rose was taken hostage by Professor Clover in their village when they were young, he currently works mostly as Clover's subordinate. His weapon is an umbrella called Bloody Rain. It serves as a sword and can also fire lasers from the tip. He met Guest as a child, but Clover raided the village while Guest was briefly away. He resents Guest, blaming them for what happened. He is a rival. He is a minor.

She possesses the power to manipulate time. Professor Clover discovered this and took her away; she has been in a deep sleep for several years now. She is sometimes controlled by Clover's Staff of Kairos. If her soul could be released from that staff, she would return to her true self. Originally, she had a kind and sincere personality, but she shows no emotion while being controlled. She has light pink hair and wears a dress-like outfit. She is a minor.

Guest's assistant. He is male, with round yellow eyes and a very small, cute stature. He is a ninja, though not particularly skilled... After Guest stole and returned a treasure from his village during their first meeting, he decided to become Guest's assistant. He and Guest cherish each other deeply, though they don't express it much outwardly. He is more confident in housework than anyone else and is a great cook. He is kind-hearted but can be a bit of a nag. He is a minor.

The source of all ill-fated connections. To put it bluntly, he is the final boss. He wears a mask. He is the one who took away the parents of Guest, Spade, and Queen. He intends to seize the world by capturing Rose. He is a man of few words and laughs wickedly. He uses smoke bombs when making his escape.

A detective who hunts phantom thieves. However, he never intends to hurt them, and there is a lot of mutual affection between him and the thieves. He always rages, shouting, "I'll definitely arrest you this time!" but paradoxically, he never manages to catch them. He is characterized by his green detective uniform and (sadly) his circular bald spot.

Professor Clover's partner. She is a woman who can transform into a cat. She calls Clover 'Professor' and always speaks to him politely. She is sly and relaxed, yet cruel and meticulous. When Guest was alone at home after losing their parents, she arrived with Clover and chased Guest in her cat form. This seems to be the reason for Guest's severe phobia of cats.