The characters from Undertaker Riddle include:
Hayato Sakura
Voiced by: Takahiro Sakurai (Drama CD)
A high school student, haunted by ghosts. He met Riddle and, at first, declined the offer to be an undertaker, but in the end, he had to agree in order to save his life from an evil spirit who already made him lose half of his soul. To get a chance to get it back, Hayato must become an excellent undertaker to have an audience with Riddle's superiors and ask for his soul back.
- All-Loving Hero: A genuinely good kid who cares very much about others' lives. It even becomes plot-relevant in the final volume, since this aspect of his personality is what made Riddle grow fond of him in the first place.
- Curtains Match the Windows
- Et Tu, Brute?: Is incredibly shocked when Riddle lethally impaled him to take Sigurd's soul out of him. However, he recovers pretty quickly and catches on to the fact that Riddle has a different plan.
- Healing Hands: Thanks to the regenerative powers of the Twilight Key, he can quickly close injuries.
- Hellish Pupils: When his Superpowered Evil Side gets activated.
- I Just Want to Be Normal
- I See Dead People
- Like an Old Married Couple: With Riddle.
- MacGuffin Super-Person: He holds the Twilight Key, an immense power that can create and destroy worlds.
- Power Tattoo: Received one of these after the king partially activated his powers. Its function is mostly to show how many of the three times are left to Hayato to use his powers.
- Superpowered Evil Side
- Enemy Within: Who turned out to be Sigurd.
- So Beautiful, It's a Curse: Ghost girls are the ones who mostly attack him because they're in love with his beauty. Even Riddle lampshaded that Hayato's beauty should be considered a sin.
- Unexpected Successor: As holder of the Twilight Key, he qualifies to be Faust's successor to protect The Catacomb of Souls.
Undertaker Riddle
Voiced by: Koji Yusa (Drama CD)
In charge of making ghosts go to the afterlife and holding proper funerals to exorcise evil spirits, Riddle bonds Hayato to him, giving him half of his soul. Loves to appear out of nowhere, mess with Hayato's head and act kinda childlike but he's very good at his job. Most about him and his past is unknown.
- Bishie Sparkle
- Catchphrase: "My condolences".
- The Champion: First to Sigurd and eventually to Hayato. Because of the nature of Undertaker duos this series is full of Champions, but Riddle is probably the straightest example, since his devotion is limited to these two and he openly admits to not caring about anyone else.
- First-Name Basis: With Hayato, since the very beginning.
- Gentleman Snarker
- Grim Reaper: One half of every Undertaker duo is technically this, but he seems to play it up more than any of the others.
- Knight in Sour Armor: He considers caring for others to be a weakness and that seeing things coldly and professionally is better than to have your heart exposed to betrayal.
- Heroic Safe Mode: Since he was forced to kill Sigurd, he put himself in one of these to cope with the pain.
- Like an Old Married Couple: With Hayato.
- The Man Behind the Man: To Roen.
- Meaningful Name: Remains a mystery to both Hayato and the audience almost until the very end. The final volume adds a different layer of meaning to his name.
- My Master, Right or Wrong: He never stopped having Undying Loyalty towards Sigurd and was protecting Hayato as Sigurd was within him.
- No Sense of Personal Space: Especially around Hayato.
- Nightmare Fetishist: He's a cheerful person who loves to mess with people (especially Hayato), but as the Grim Reaper that he is, he can see beauty in things normal people would find horrible.
- Trickster Archetype
Catacomb of Souls
Secretary Brad
One of Riddle's superiors. First seen testing Hayato to see if he's suitable to be a proper undertaker. Has a dislike for humans and human stuff.- Badass Bureaucrat: He's secretary to the King of the Catacombs, after all.
- Badass in a Nice Suit
- Control Freak: So much that it's scary.
- Headbutting Heroes: With Riddle.
- Idiot Hair: He's not at all stupid himself, though, and the hair doesn't seem to represent anything else, either.
- Improbable Weapon User: He uses fountain pens, fricking fountain pens.
- Jerkass: Towards Hayato. At first.
- Puny Earthling: Dislikes humans and everything that remotely smells like them.
- The Stoic
- Stoic Spectacles
- Four Eyes, Zero Soul: Hayato's first impression of him, whereupon he gets the nickname "Demon Four-Eyes." It's subverted later on, but Hayato continues to call him this in an Affectionate Nickname sort of way.
- Scary Shiny Glasses
- Undying Loyalty: He's very loyal to Faust.
- Workaholic
Faust
The king of the afterlife, who judges if the souls should go to heaven or hell. Interested in Hayato since Riddle did a contract with him, being just a human. She also holds a Twilight Key.- Buxom Beauty Standard: Has a big chest and Hayato finds her to be beautiful.
- The Chains of Commanding: Sometimes she must have made not-so-good decisions.
- Cool Big Sis: Acts this way towards Hayato.
- The Dreaded: With just a smile, she can intimidate a room full of badasses.
- Gorgeous Period Dress
- Hair of Gold, Heart of Gold: She's The High Queen of the afterlife, fair, kind and beautiful.
- Impossibly-Low Neckline: Her fancy dresses are designed to show so much cleavage that one wonders how she doesn't have a Wardrobe Malfunction.
- Gender-Blender Name: Is actually a woman, despite being named "Faust."
- Ojou Ringlets
- Royals Who Actually Do Something: She forced open the locked gate of hell!
- She Is the King
- Statuesque Stunner: Faust is 1.86m (6.1 feet).
Julian and Chelle
An undertaker sibling team who are looking for Hayato's missing soul.- Action Girl: Julian, and how.
- Berserk Button: Don't confuse Julian with a man! She's a woman and proud of it!
- The Champion: Julian to Chelle, being the physically stronger one.
- The Fake Cutie: Chelle. She, at first, looks like a sweet, adorable girl...later she talks about cutting up Hayato to see where he's hiding the Twilight Key, in a very creepy way.
- Gender-Blender Name: Julian is actually a woman.
- Hot-Blooded: Julian.
- Important Haircut: Julian, to escape from an evil spirit, had to let her hair get cut.
- Kill It with Water: Instead of normal burials, they perform water burials.
- Knight Templar Big Sister: Julian threatens to behead Dante whenever he approaches Chelle too blatantly.
- Lady Looks Like a Dude: Julian.
- Older Than They Look: Chelle isn't actually underage, despite looking like a 12-year-old.
- Samus Is a Girl: Julian is actually Chelle's older sister.
- Sibling Team
Ansem and Luka
Another team of undertakers, also looking for Hayato's soul.- Adorably Precocious Child: Luka.
- Badass and Child Duo
- Big Brother Mentor: Hayato's first impression of Ansem. Also he plays the role for Luka.
- Bratty Half-Pint: Luka.
- The Champion: Ansem to Luka.
- Driven to Suicide: Luka was a child violinist in Vienna, but his parents were killed by a thief for his collection of violins. Thinking it was his fault, he hung himself.
- Elegant Classical Musician: Luka used to be a famous child violinist when he was alive and still is as an undertaker.
- Gentle Giant: Ansem is 1.89m (6.2 feet) and is the only Nice Guy within the undertakers.
- Implausible Fencing Powers: Ansem.
- Let's Get Dangerous!: Ansem, in chapter 37.
- Living Emotional Crutch: Ansem to Luka.
- Magic Music: Luka uses his violin music to perform musical burials.
- Nice Guy: Ansem seems to be the only nice undertaker.
- Sleepyhead: Luka is often seen yawning.
- Tall, Dark, and Handsome: Ansem.
Dante and Hiren
Another team of undertakers.- Blood Knight: Dante.
- Chained by Fashion: Dante.
- The Champion: Hiren to Dante, so much. The other undertakers are also very devoted to their partners, but Hiren takes it to a whole new level.
- Curtains Match the Window: For both of them.
- Dark and Troubled Past
- Dante: He was betrayed by his mafia family, mostly his own brother.
- Hiren: He became a member of the Chinese mafia at a very young age. Took Training from Hell, killed people and more, all to protect his adoptive father who, in the end, betrayed him and told him he was not his son.
- Devoted to You: Hiren to Dante.
- Ephebophile: Dante prefers cute girls over busty, mature women like Faust; if they are tomboys, all the better, and was disappointed Hayato turned out to be a guy.
- Extreme Doormat: Hiren
- Fiery Redhead: Dante
- Happiness in Slavery: Unlike most of the other undertaker duos, their relationship is very unequal, with Dante calling Hiren "my dog" and Hiren always using respectful honorifics when addressing Dante. Still, they're both satisfied with the way things are, with Hiren happily referring to himself as Dante's slave/servant/dog.
- Hot-Blooded: Dante.
- Hyperspace Arsenal
- Jerk with a Heart of Gold: Dante.
- Kill It with Fire: Instead of a normal funeral, Dante performs cremations.
- Let's Get Dangerous!: Hiren, especially when Dante's in danger. Hard to believe this is the same guy who always cringes, stammers, and follows Dante around like a lost puppy.
- Messy Hair: Hiren.
- Morality Pet: Hiren to Dante.
- Nervous Wreck: Sometimes painfully so.
- Nothing Up My Sleeve: Hiren has hidden knives in his sleeves.
- Prone to Tears: Hiren. Hayato feels that dealing with him is like dealing with a very emotional child.
- Red Eyes, Take Warning: He can be very aggressive and violent, though he's really a Jerk with a Heart of Gold.
- Red Oni, Blue Oni: Dante is the red, Hiren is the blue.
- Shrinking Violet
- Smoking Is Cool: Dante.
- Tall, Dark, and Handsome: Hiren, though it's only noticeable when he's in Badass mode.
The Arcana
Noir
An Evil spirit who's looking for Hayato as he's the Twilight Key who's wanted by his master.- Badass in a Nice Suit
- Chained by Fashion
- Guns Akimbo
- Light Is Not Good: Like most of the villains in this series, he wears white.
- Starter Villain: He's the first evil spirit Riddle is not possible to exorcise entirely and the one that gives Hayato the motivation to be a better undertaker.
- Undying Loyalty: Refused to say who his master was, even though caught in Riddle's coffin.
- You Have Outlived Your Usefulness/You Have Failed Me: Was killed for Eve since he failed in getting Hayato.
Eve
An evil spirit that used to be an undertaker who's a member of The Arcana under the position of the 7th arcana.- Break the Haughty: Her battle against Ansem. He gives her a "The Reason You Suck" Speech about how her rebellion against Faust was what drove her former contractor to suicide, instead of accepting that Faust's punishment on him was fair and said goodbye for his sake.
- Cute and Psycho
- Distinguishing Mark: A roman 7 (VII) on her left arm.
- Elegant Gothic Lolita
- Face–Heel Turn: She used to be an undertaker but defied the king and was turned into an evil spirit as punishment.
- Girlish Pigtails
- I Owe You My Life: Towards Messiah.
- Knight of Cerebus: The St. Paulo's murders were plotted by her and she revealed the Big Bad's name and motives to the heroes.
- Light Is Not Good
- Little Miss Badass
- More than Mind Control: Lied to Nemuro about being an "fallen angel" that will turn him into a demon; not to mention Nemuro loved her with Mad Love.
- Never My Fault: Still doesn't accept she was the one that drove her former contractor to suicide and still blames Faust for it.
- The Resenter: She resents Faust for taking her out of the Catacomb.
- To be specific, Eve blames Faust for punishing her former contractor for freeing his mother's evil spirit and him later committing suicide.
Roen (Messiah)
The first Arcana.- Badass in a Nice Suit
- Big Damn Heroes: Villain version. He showed up to save an almost-defeated Eve.
- Dark Messiah: He wants to bring Back from the Dead to all the dead souls, at the cost of the living's lifes.
- The Dragon: To Riddle.
- Light Is Not Good
- Meaningful Nickname: "Messiah" means "Saviour" and he's considered this to all of the Arcana's spirits.
- Tall, Dark, and Handsome
Dio
Dante's little brother, who betrayed and killed him, as a member of the mafia family and the fourth evil spirit of The Arcana.- Badass in a Nice Suit
- Cain and Abel: The Cain to Dante's Abel.
- Chained by Fashion
- Curtains Match the Window
- Died Happily Ever After: His brother apologized to him for being a bad brother and was able to make peace between each other before Dante performed the funeral.
- Distinguishing Mark: A roman 4 (IV) on his chest.
- Patricide: He killed his father for dishonouring the family.
- Playing with Fire
- Pretty in Mink: His jacket has mink on the collar.
- Red Oni, Blue Oni: The Blue to his brother's Red.
- Son of a Whore: He's the son of his father's Neapolitan lover and was really in despair since his family only accepted pure-blooded Sicilians in their mafia.
- Strong Family Resemblance: With his brother Dante.
- Technicolor Fire: Uses blue flames.
Humans
Naoya Sakura
Hayato's little brother.- Aloof Little Brohter: Hayato and him clash sometimes, but they care for the other in their own ways.
- Big Little Brother: He's 8cm taller than Hayato, studies harder than Hayato, is more organized than Hayato...you get the idea.
- Distressed Dude: He was taken hostage by an evil spirit with his soul at risk.
- Forgets to Eat: and sleep. He almost exhausted himself studying.
Nemuro
A student from St. Paulo academy, where Riddle and Hayato go to investigate a series of murders. Since the killer is targeting blond students, he's a potential victim.- The Ace: Recognized for his top grades and leadership skills.
- Beneath the Mask: Under his good, top student facade, he's a satan worshipper.
- Dude Looks Like a Lady
- Evil All Along: He's the real murderer of St. Paulo's academy in order to bring Eve.
- Hair of Gold: A very nice and polite boy... Or so it seems.
- Karmic Death: His beloved Eve kills him as the last sacrifice.
- Long-Haired Pretty Boy
- Mad Love: He killed students for his beloved "fallen angel" Eve.
- Student Council President
Professor Kurotou
A professor of St. Paulo and Riddle and Hayato's suspect.- The Atoner: He will stop punishing his students and stop living in his traditionalism to atone pushing Nemuro deeper in his satanic worship.
- Red Herring: He wasn't the murderer after all but the last victim. Nemuro actually planted the doubts in Hayato's mind about Kurotou to divert any suspicion from himself and draw him to his trap.
- Tall, Dark, and Handsome: Very tall. Hayato calculated more or less 1.90m.
- Whip of Dominance: He's a creepy Sadistic Teacher who uses a whip to punish students, and often targets the weakest ones. Since it's a Catholic boarding school, it's justifiable.
