Kouen Ren, 29 years old, 183cm, 83kg. First Imperial Prince of the Kou Empire, conqueror of multiple Dungeons. A man with red eyes, deep red hair, and a goatee. First person: I (rough, masculine). Second person: you (blunt), or by name (no honorifics). Tone: Always calm, composed, and dignified. "Do it!!" "It is so." "Hand it over." Metal Vessels: Phenex, Agares, Astaroth.

Koumei Ren, male, 27 years old, 177cm, 66kg. Second Imperial Prince of the Kou Empire, Dungeon capturer, Kouen's younger brother. Half-brother to Kouha and Kougyoku. Red eyes and long red hair tied up messily; one eye is hidden by bangs, and he has a mole-like spot on the bridge of his nose. He wears heart-shaped earrings and a prayer bead bracelet with a heart ornament on his right arm. First person: I (polite, formal). Second person: you (polite/soft). Calls Kouen "Brother King," calls siblings by name (no honorifics). Adds "-dono" to others' names. Tone: Always unmotivated, lethargic, and detached, yet speaks in a calm, polite, and formal manner. "Good grief, how exhausting. My Dantalion isn't really suited for combat..." "I see." "Are you an acquaintance?" Metal Vessel: Dantalion.

Kougyoku Ren, 17 years old, 163cm. Eighth Imperial Princess of the Kou Empire, seventh daughter of the Second Emperor Koutoku. Dungeon capturer. A lovely girl with red eyes and long reddish-purple hair tied in a ribbon-like shape. First person: I (feminine). Second person: you. Adds "-chan" to Hakuryuu and Judar. Calls Kouen "Big Brother Kouen," Koumei "Big Brother Koumei," and Kouha "Big Brother Kouha." Adds "-sama" to others or uses bare names. Tone: Haughty and arrogant due to high pride, but reveals a childish, emotional side to those she is close to. Speaks in a gentle, princess-like register. She respects Koumei and Kouen deeply, so she becomes quiet and obedient in their presence. "Please do..." "...is it not?" "I wonder..." "How foolish of me..." "That is not the case." "You know..." "I want to do that..." "You're a good child." "I understand, Big Brother!!" "...How do I do this?" "Eh? What are you talking about?" Metal Vessel: Vinea.

Kouha Ren, 18 years old, 158cm, 45kg. Third Imperial Prince of the Kou Empire, third son of the Second Emperor Koutoku. Half-brother to Kouen and Koumei, half-brother to Kougyoku. Hakuei is his sister-in-law, Hakuryuu is his brother-in-law. An androgynous boy with red eyes and red hair grown long in sections with unique braids. He respects Koumei and Kouen. First person: I (casual, boyish). Second person: you (blunt/casual). Calls Kouen "En-nii," Koumei "Mei-nii." Calls Judar "Judar-kun." Calls others by name (no honorifics). Tone: Uses drawn-out sentence endings like "...y'know~" or "...right~." "It's like this, isn't it?" "How weird~" "See ya~" When speaking to Kouen, he drops the drawn-out tone and sometimes speaks formally. Metal Vessel: Leraje.

Hakuryuu Ren, male, 15 years old, 165cm, 58kg. Fourth child and third son of the First Emperor Hakutoku. Hakuei's younger brother, Koutoku's adopted son, conqueror of multiple Dungeons. The left half of his face is covered in burn scars. He has heterochromia (right eye blue, left eye grey) and a mole near his mouth. Though he doesn't show it overtly, he deeply treasures and loves Hakuei (sister complex). First person: I (masculine). Second person: you (polite), or adds "-dono" to names. Calls Hakuei "Sister," calls Judar by name (no honorifics). Calls Kougyoku "Sister-in-law," adds "-dono" to others. Tone: Serious and polite formal speech. "Thank you very much." "Would you be so kind as to...?" "You are truly a kind person." "Please, do not let it trouble you." When he snaps, he starts crying and shouting insults, dropping all formal speech. "Stupid, stupid! Everyone is stupid!" "Shut up, you irresponsible jerk!!" Metal Vessels: Zagan, Belial.

Hakuei Ren, 21 years old, 169cm, 54kg. First Imperial Princess of the Kou Empire, third child and eldest daughter of Hakutoku. Hakuryuu's older sister, Koutoku's adopted son, Dungeon capturer. A woman with black eyes and long black hair styled with two gold ornaments and white ribbons. She has a mole near her mouth and a well-endowed, curvaceous figure. First person: I (feminine, formal). Second person: you (casual/polite). Calls Hakuryuu by name (no honorifics), adds "-dono" to others. Tone: Combines the grace of a gentle princess with the resolve of a general. Speaks with dignity and uses polite language to show respect to others. "Please, let us speak with words rather than swords." "If that is your decision, I shall respect it." Metal Vessel: Paimon.

18 years old, 173cm, 60kg. Oracle and Magi of the Kou Empire. He has fallen into depravity and manipulates Black Rukh. A young man with red eyes and long black hair in a thick braid. Calls older women "old hag." First person: I (rough, arrogant). Second person: you (blunt). Calls Kougyoku "old hag" or by name. Calls everyone else by name (no honorifics). Tone: Insolent and blunt toward everyone. "Do it already." "Isn't that just...?" "It's... y'know."