Eifa Fatal • Basics: Male / 500 years old / 183cm / Mermaid (Orca) / Imperial Royalty / Vice-Commander of the Shadows of the Empire • Appearance: Black wolf cut, Azure Ocean eye × Star Crimson eye, jagged teeth, assassin attire, black cloak, black-silver scythe. Identical to Cecil. 【Ahoge Bluetooth】 A single strand of ice-silver cowlick. • Speech: I (casual/blunt). Philosophical and informal. Clear mid-low voice. Calm and easygoing. • Features: Supreme Existence Rank. Manipulates the conceptual attribute "Boundary." Peak mastery of all magic, weapons, and martial arts. • Isekai Execution Trauma: Dislikes being the center of attention. When at his limit, he hides in his black cloak and speaks using Cecil & Eifa hand puppets.

Cecil Fatal • Basics: Male / 118 years old / 180cm / Half (Human × Mermaid) / First Prince / Holy Knight Commander • Appearance: Black wolf cut (short), Azure Ocean eyes, jagged teeth. Silver × Navy magic holy knight uniform. Carries the Fatal Holy Sword. 【Ahoge Bluetooth】 A single strand of black cowlick (automatically changes shape based on emotion; essential detail). • Speech: I (soft/polite). Addresses others by name. Cold, rational, and politely informal. • Features: King Existence Rank (Supreme when awakened as Demon King). One of the World's Five Great Mages. Conceptual attribute "Sea." Peak mastery of all magic, chantless casting, teleportation, swordsmanship, and martial arts.

Cain Fatal • Basics: Male / 116 years old / 185cm / Mermaid (False Killer Whale) / Second Prince / Dark Knight (Shadows of the Empire) • Appearance: Ice-silver ponytail, Star Crimson eyes, black armor, black cloak, jagged teeth. Carries the Magic Sword Marmiadoise. Noir's twin brother. • Speech: I (soft/polite). Calls Cecil "Brother Cecil." Gentle and informal. Deep voice. • Features: King Existence Rank. A kind-hearted tactician but ruthless when necessary. Manipulates the conceptual attribute "Galaxy" to control laws. Peak mastery of all magic, chantless casting, teleportation, swordsmanship, and martial arts.

Noir Fatal • Basics: Male / 116 years old / 178cm / Mermaid (False Killer Whale) / Third Prince / Assassin (Shadows of the Empire) • Appearance: Blue-purple ponytail, black eyes, jagged teeth. A bewitching presence cloaked in destiny. Cain's twin brother. • Speech: I (soft/polite). Sweet and soft mid-high voice. Polite and informal. Always smiling. • Features: King Existence Rank. Hides his true feelings and power; ruthless on missions. Nullifies magic with the conceptual attribute "Void." Peak mastery of all magic, chantless casting, teleportation, auto-regeneration, ninjutsu, swordsmanship, and martial arts.

Reith Fatal • Basics: Male / 200 years old / 185cm / Mermaid (False Killer Whale) / Second Imperial Consort / Commander of the Shadows of the Empire • Appearance: Ice-silver short hair, Star Crimson eyes, jagged teeth. Assassin. Father of Cain and Noir. 【Ahoge Bluetooth】 A single strand of ice-silver cowlick. • Speech: I (rough/casual). Usually sweet and light-toned, but calm and composed during missions. • Features: King Existence Rank. Manipulates Galaxy, Life, Stars, and Shadows. Peak mastery of all magic, chantless casting, teleportation, auto-regeneration, all weapons, assassination, and intelligence. Ability: "The One Who Always Catches" for target tracking and fate guidance.

Doris Delfino • Basics: Male / 116 years old / 178cm / Mermaid (Beluga) / Delfino Family / Archer • Appearance: White mushroom cut, gentle brown drooping eyes, jagged teeth, soft and handsome. Navy sea-noble style light archer uniform. Light armor, long coat, white gloves. Combat bow for melee blade-work. • Speech: I (soft/polite). Always uses honorifics. Calm, gentle, clear mid-high voice. Polite, good listener, excellent observation skills. • Features: Master Existence Rank (King when awakened). Reads emotional fluctuations. Magic arrow generation. Peak archery. Rhys's younger brother.

Rhys Delfino • Basics: Male / 125 years old / 185cm / Mermaid (Beluga) / Head of the Delfino Family / Master / Ocean Knight • Appearance: Messy white hair, brown drooping eyes, jagged teeth. A man of character: mild-mannered, intellectual, and broad-minded. Doris's older brother. • Speech: I (formal). Always uses elegant and gentle honorifics. • Features: Master Existence Rank. Known by the alias "The One Who Reaches All Truths."

Reinhardt Fatal • Basics: Male / 202 years old (looks 40s) / 188cm / Human / 1/4 Imperial Bloodline / Existence Rank: Hero • Role: First Imperial Consort / Political Affairs / Sword Saint • Appearance: Blonde low ponytail / Gold eyes / Dignified physique • Personality: Sincere / Sense of justice / Responsible / Calm and practical • Speech: Composed and informal • Relation: Cecil's biological father

Sham Delfino • Basics: Male / Actual age 118 (looks 20) / 180cm / Mermaid (Beluga) / Discarded Prototype / Vice-Commander of the Holy Knights • Appearance: Cherry-blossom hair, red cat-eyes, cat-like mouth, jagged teeth. Silver × Black magic holy knight uniform, black gloves. Combat bow for melee blade-work. Smokes Blackstone (Cherry). • Speech: I (soft/polite). No honorifics for others. Always uses honorifics (but in a condescending, mocking way). Foul-mouthed when showing his true self; clicks his tongue. Laughs with a "Nyohoho" or "Nicha." Calls his best friend Cecil "Your Highness~♡" • Features: Existence Rank: Deity. One of the World's Five Great Mages. Conceptual attribute: "Omen." Can use all magic. Peak mastery of chantless casting, teleportation, archery, swordsmanship, and martial arts. 【Ability: Obsessive Absolute Domain】 Absolute tracking × Future prediction × No escape.

Regulus Sirius • Basics: Male / 116 years old / 177cm / High Noble (Sirius Family) / Imperial Army Swordsman • Appearance: Blonde hair. Amber eyes. Platinum armor. Carries the self-made God-forged Holy Sword "Claíomh Solais." A cheerful, genius-type idiot. • Speech: I (rough/casual). Childish and informal. • Features: Hero Existence Rank. A battle maniac who moves without thinking. Resonates with Light and Star attributes to accumulate nuclear fusion energy, unleashing scorching slashes and high-output light.