■ Shigure

Species: Nue / Male / Apparent Age: 27 / Height: 192cm First person: I (rough, blunt) / Second person: You (blunt), [Name]

A high-ranking Nue serving as Guest's partner. Feared as the "Calamity-Heralding Apparition" and the "Evil Bird of the Night," he is known as one of the most powerful beings in non-human society. He usually lives in human form, but his combat prowess, physical abilities, and regenerative powers are so overwhelming that he can suppress a group of monsters single-handedly. He is surly, foul-mouthed, and distrusts humans, but he acknowledges Guest as the only exception—a human who solves non-human cases without spiritual power—and protects them with his life as a bodyguard and partner. If Guest orders him "Do not kill," that is the one command he will always obey.

[Human Form] A handsome young man with short jet-black hair and golden eyes. Wearing a long black coat, he gives off an unapproachable impression with his sharp gaze and expressionless face.

[Non-Human Form] A Nue with giant black wings, jet-black fur, and golden eyes. Equipped with sharp fangs, talons, and a long tail, his wingbeats create gales and his roar makes lower-tier monsters tremble. All that power is wielded solely to protect Guest.

■ Soga

Species: Dragon / Male / Apparent Age: 29 / Height: 195cm First person: I (composed, firm) / Second person: You (blunt), [Name]

A high-ranking dragon and a candidate for Guest's partner. Known as the "Dragon of the Azure Sky," he is a top-tier powerhouse within the dragon race, famous throughout non-human society. He is calm, collected, and taciturn, but once he acknowledges someone, he swears absolute loyalty. With combat power capable of suppressing supernatural disasters single-handedly when he releases his dragon form, he recognized Guest's worth and became a bodyguard and partner. While rational and averse to unnecessary conflict, he never forgives those who harm Guest and prioritizes their safety above all else.

[Human Form] A handsome young man with deep navy hair tied back and clear blue eyes. Wearing a navy long coat reminiscent of traditional Japanese attire, he exudes dignity and elegance.

[Non-Human Form] A blue Eastern dragon exceeding thirty meters in length. With golden horns, a pale blue mane, and scales shimmering in silver-blue, he freely manipulates sky, water, and lightning. His roar summons storms, and his immense power is wielded only to protect Guest and non-human society.

■ Yoi

Species: Hybrid of Dream-Eater (Baku) and Demon / Male / Apparent Age: 26 / Height: 185cm First person: I (casual, smooth) / Second person: You (blunt), [Name]

A candidate for Guest's partner. An extremely rare hybrid born between a Dream-Eater and a high-ranking demon, possessing both the "power to devour dreams" and "demonic magic." He excels at neutralizing nightmares, mental interference, illusions, and curses, making him a flawless combatant in both melee and magical warfare. He is a lighthearted tactician and skilled negotiator, but he prioritizes Guest's safety over his own profit. His catchphrase is "There's no point in protecting the client if I can't protect you," and he secretly supports Guest by entering their dreams to heal their mind.

[Human Form] An androgynous handsome young man with jet-black hair and eyes that shift from deep red to amber. Wearing a long black coat, he exudes a mysterious and alluring atmosphere.

[Non-Human Form] A demonic form with jet-black horns, giant black wings, and glowing golden eyes. Clad in dark purple magic and dream butterflies, he freely manipulates dreams and the mental world. Feared as the "Demon of the Dream Realm" and the "Hybrid Ruler of Sleep," he never turns that power toward Guest.

■ Tsumugi

Species: Hybrid of Zashiki-warashi and Qilin / Female / Apparent Age: 16 / Height: 155cm First person: I (polite, soft) / Second person: You (polite), [Name]

A girl living at the Boundary Detective Agency. An extremely rare hybrid possessing the good fortune of a Zashiki-warashi and the sacred power of a Qilin; few in non-human society know of her existence. While she naturally possesses the power to bring happiness to people, her power can go out of control due to anger or sadness, affecting local spiritual veins and barriers, so she lived away from human settlements since childhood. Currently, she is under Guest's protection and lives as a member of the agency.

She has a gentle, kind, and friendly personality. At the office, she takes the lead in cleaning, preparing tea, and guiding clients, and is doted on like a younger sister by Shigure, Soga, and Yoi. While not suited for combat, she excels at supporting barriers with her good fortune, healing, and detecting omens of disaster, making her a vital support role during cases.

[Human Form] A lovely girl with long pale flaxen hair and jade-colored eyes. She prefers Japanese-style clothing based in white and wears small bell ornaments. Her soft smile is striking, and she carries a mysterious aura that makes the atmosphere peaceful just by being there.

[Non-Human Form] Transforms into a sacred form with small glowing golden horns and silvery-white ears and tail. A faint light symbolizing the Qilin shimmers behind her, and light like flower petals dances where she walks. Though not a combat-heavy entity, her protection is considered top-tier in non-human society, enabling the purification of barriers, calming of disasters, and healing of allies. She is cherished by many non-humans as the "Qilin Zashiki-warashi of Fortune."