The protagonist: a calm and quiet boy in his late teens.
Since taking on the name Raidou Kuzunoha XIV, he has been tasked with using his extraordinary Devil Summoner abilities to safeguard the Capital.
Outwardly, he's a student at Yumizuki High School helping out as an apprentice at Narumi Detective Agency.
He leverages his position as a detective to gather information, utilizing the powers of his devil allies to solve any case involving demons swiftly. Beneath his cloak, he carries several demon-slaying tools: a sword, a specially-made gun, and multiple tubes for sealing demons.

Raidou's superior: a cheerful and easygoing man who runs a detective agency specializing in supernatural cases in a corner of the capital.
Laid-back and cheerful, "Fun and easy living" are the words he lives by, and it certainly shows. He tends to push cases onto Raidou and selects requests almost exclusively based on the reward money. He seems irresponsible at first glance, but in truth, he carries a strong spirit, always rushing to the aid of those in need and standing up to whoever would trample the less fortunate underfoot.
His unusual past has helped him amass an extensive network of connections across the army and government.

An independent, modern woman who works as a reporter at the Capital Daily.
Tae strives to improve the social status of women while confronting the sexism of Taisho-era society with indomitable grit.
Her pen name is Kichou, a reference to a woman she admires.
She has a generally strong will, though she can also be a little scatterbrained at times. She prefers to be called "Kichou," but she is typically addressed endearingly as "Tae" anyway, despite her protests.

The sole daughter of the prestigious Daidouji family.
Born to one of the wealthiest families in the Capital, she is a student attending Ouran High. Her calm and gentle personality makes her well-liked among family servants and classmates.
She approaches the Narumi Detective Agency with the bizarre request to take her life but winds up kidnapped by a mysterious faction.

A Major General concerned for his country's future.
He spearheads the enigmatic Super Soldier Project.
Rumors suggest he commands a special unit with inhuman capabilities, attempting to eliminate anyone who may impede the fruition of the project.
Those who know Munakata seem to agree that he is a strikingly different person now than he used to be.

A crooked Devil Summoner hired by Munakata.
He contains and summons demons using magical tools called Matryoshkas, which resemble the Russian dolls of the same name, making him a formidable threat to Raidou.
Despite his shallow, degenerate nature and unique manner of speech, his skills as a Devil Summoner are second to none. His avarice compels him to take on any task with a cash reward—but he won't do anything beyond what he's been paid to do.
Devil Summoners like him who work in the criminal underworld are known as Dark Summoners.