Black Cat Wiki
Whether friend's or foe's...I never grow accustomed to news of death.

—Sephiria Arks, Chapter 86

Sephiria Arks
Biographical Information

セフィリア アークス


Sefiria Aakusu

Also known as

Number I
Sephy (by Jenos Hazard)

Basic Information





January 1

Blood Type



170 cm (5'7")

Hair Color


Eye Color



Japanese cuisine and culture



Professional Information





Chapter 42


Episode 1

Voice Actors
Japanese Voice

Kikuko Inoue

English Voice

Lydia Mackay

Image Gallery

Sephiria Arks (セフィリア アークス Sefiria Ākusu), known as Number I, is the commander of the Numbers and is trusted enough by Chronos to be given total control over killing Creed. Sephiria was one of the few members who were "born for Chronos".


Sephiria has long, wavy ash blonde hair and pale blue eyes. She has the Roman numeral I tattooed on her forehead, outlined by a lightning bolt on each side. She wears gold shoulder pads reminiscent of a Spanish soldier, and a pink suit jacket with a long, flowing skirt.


In the manga, Sephiria has a very calm, tranquil demeanor. She is one of the most intelligent, skilled fighters yet she never lets her emotions get the best of her. She appears to enjoy Japanese cuisine and culture, as she is seen meditating and carrying on business in a Japanese-style environment several times. She was born and raised to serve Chronos and thus she takes her duties to the organization very seriously. Sephiria often manipulates others into helping Chronos fulfill its goals, especially Train Heartnet. She certainly has a ruthless side to her and has no problem demonstrating it to troublemakers like Creed Diskenth.

In the anime, Sephiria has a more intense, slightly less calm demeanor and is completely focused on serving the needs of Chronos. She has confronted Train several times about deserting Chronos and does occasionally let her feelings lead her in the heat of battle.


Sephiria Arks was brought up to serve Chronos. Her body was modified to withstand all injuries inflicted on it.

When Train officially became a Chronos Number, Sephiria handed him the orichalcum gun, Hades.

Years later, Train began sparing the lives of his targets, disobeying Chronos' orders. Sephiria ordered Belze Rochefort to investigate. He complied and reported that a sweeper woman by the name Saya Minatsuki may have had something to do with the Black Cat's sudden change. Later, Sephiria watched as Train was sentenced to ten days of confinement and would not see him again until his sentence was over.


Revolution Arc

Sephiria is commanded by the Chronos Elders to destroy the Apostles of the Stars after the leaders at the world conference are all assassinated.

The Mad Gunman Arc

She and Belze Rochefort visit ex-Number Train Heartnet and ask him to capture Creed alive as a sweeper. The commander presents Train with the bounty notice promising 3 billion dollars for Creed's arrest and leaves him to consider her offer.

Cerberus Arc

Keen on utilizing as many resources as possible against the Apostles, Sephiria sends Jenos to recruit Rinslet Walker. She later meets with Rinslet to assess her personality and capabilities. Rinslet is dubious of Sephiria's position as the Numbers' leader and is rather disrespectful at first. After she realizes that she's being put through an evaluation (as well as being mocked by Number I), she attempts to quit. However, Sephiria blithely informs her that she cannot back out of the job and compels Rinslet to work with Cerberus and act as a mole to get inside Creed's base.

Lucifer Arc

After the fiasco that Kranz Maduke and Baldorias S. Fanghini cause in Stock Town, Sephiria asks Jenos to bring Kyoko Kirisaki to her. Apparently Kyoko has turned over a new leaf because of Train and is no longer an Apostle, but the commander wants to be sure the teenager is not deceiving everyone. Using her Christ Saber, she quickly carves a tombstone with Kyoko's name on it and tells her she will be assassinated unless she would like to become a Chronos Eraser. Kyoko refuses because she promised Train she wouldn't kill anymore. Relieved by her answer, Sephiria destroys the tombstone and tells her that she was testing her to see if the promise was actually true.

Alliance Arc

Later, she goes head to head with Creed and stands a pretty good chance against him. She makes multiple hits that are capable of killing the insane man several times over. Unfortunately since Creed has gained immortality through

Sephiria vs Creed

the power of nanomachines, she cannot defeat him. In a desperate attempt for victory she unleashes her ultimate attack. Creed manages to dodge by forcing his Imagine Blade up to level 3. Her attack took up a large amount of her strength and Creed easily takes her down. Train interrupts the battle as Creed is about to kill her.

Sephiria appears as Train finally defeats Creed and waves off his concerns about her. Apparently her body has been reinforced to withstand significant damage shortly after she was born.

A Carefree Tomorrow

After everything that happened, Sephiria peacefully meditates.

Equipment and Abilities

Sephiria's sword.

Master Swordsman: In battle, Sephiria wields Christ, a falchion sword made out of Orichalcum. Her swordsmanship is great enough to contend with long range weapons like multiple arrows, machine guns, bazookas and even Hades. She can juggle a full glass on the tip of her blade without spilling a single drop, carve stone and shatter boulders and buildings, all with little to no effort. She also crossed swords with Creed Diskenth and dominated the fight in terms of skills, only losing their battle because of Creed being enhanced with both Tao and nanomachines of immortality.

Immense Speed: Sephiria can move so fast that at least three after-images are left behind when she moves. She specializes in lightning-fast charges and strikes for deadly effect.

Accelerated Healing Factor: Sephiria's body was genetically enhanced to sustain any injuries inflicted on it.


Train Heartnet

In the anime, Sephiria resents Train for leaving Chronos and repeatedly attempted to convince him to rejoin, only to fight him when he refused. She did not understand his decision until Train succeeded in defeating Creed without killing him. They eventually got along, and fought alongside one another during the Eden Arc.

In the manga, Sephiria does not harbor any ill will towards the former number, and seeks his help with the situation involving Creed.

Jenos Hazard

The two seem to be close, seeing as how Jenos often refers to her as"Sephy".

Creed Diskenth

Sephiria sees Creed as a threat to humanity, and for maintaining peace. She believed his plan is outrageous, and insane, and that Creed must be taken out no matter the cost.


  • She is the only female member of Chronos (That is not the case in the Latin American dub, however, where Lin is also a female.).
  • Sephiria may have been based on Joan of Arc, seeing as she is a skilled swordswoman who leads a special military unit of assassins, and is dedicated to Chronos (like how Joan was dedicated to her country). Her surname may also be a homage to the maid of Orléans.
  • She is one of the few known numbers to have been raised by Chronos.
  • Sephie Michaela Deviluke's appearance, a To LOVE-Ru character, is based on Sephiria's appearance.


Main Train Heartnet  |  Sven Vollfied  |  Eve  |  Rinslet Walker
Independent Saya Minatsuki
Sweepers Alliance River Zastory  |  Kevin McDougall  |  Silphy Dearcroft  |  Lacdoll  |  Gallom
Elders Willzark
Chronos Numbers Sephiria Arks  |  Belze Rochefort  |  Emilio Lowe  |  Kranz Maduke  |  Nizer Bruckheimer  |  Anubis  |  Jenos Hazard  |  Baldorias S. Fanghini  |  David Papper  |  Ash  |  Lin Shaolee  |  Beluga J. Heard  |  Mason Ordrosso
Chronos Erasers Clevar
Other Karl Walken
The Apostles of the Stars
Main Creed Diskenth  |  Shiki  |  Echidna Parass  |  Kyoko Kirisaki  |  Charden Flamberg  |  Durham Glaster  |  Leon Elliot  |  Maro  |  Doctor
Other Deek Slasky  |  Preta Ghoul  |  Eathes  |  Igor Planter  |  Gyanza Rujike
Other Torneo Rudman
Other Annette Pias  |  Woodney  |  Tearju Lunatique  |  Tim Vertical  |  Layla  |  Saki  |  Zagine Axeloake

 |  Kelly Barris  |  Morris Flitt