Under Night In-Birth Wiki


Chaos (ケイアス)
Kei Asuma (明日真 景)




December 5th


174 cm (5'8½")


57 kg (125 lbs)




Bloodstained Chaos [Bloody Chaos]




Battle Style


The EXS of Illusion: "Umbral"


Codex of Disorder: Chaos Code

Voice Acting

Japanese Voice:

Yoshitsugu Matsuoka

"Please... This logic is both basic and primitive.
One must be in the control tower, where
precise decisions lead to victories."

Chaos (ケイアス) is a tactician who works for the organization Amnesia as its de-facto second in command.

On the battlefield, some know him by his full alias Bloody Chaos (血塗れの混沌(「ブラッディ・ケイアス」)), but he himself isn't fond of it. His real name is Kei Asuma (明日真 景).

He was introduced in the arcade launch of UNDER NIGHT IN-BIRTH Exe:Late.


Claws of Strategy, "The Bloodstained Chaos"

The boy who allegedly handles most of the day-to-day operations of Hilda's organization, Amnesia, moving people around like pawns. He has what appears to be a close relationship to Gordeau, who has since left the organization. But now, he has set his eyes on the Licht Kreis, Amnesia's greatest threat. Or, more specifically, he searches for the Crimson Knight, Gordeau's hunter. Now, he sets foot onto the battlefield.[1]


Chaos is a very good friend of Gordeau. He does all kinds of paper work and plans for Amnesia and rarely comes out of his own room. His personality is calm and collected, but he still often jokes around with Gordeau. Chaos also tends to be quite the worrywart when it comes to Gordeau, and he sometimes disregards blunt tactics.

However, in his past and on the battlefield, some know him by the nickname of the Bloodstained Chaos. His simple name of "Chaos" however, was a last minute naming for himself upon his first direct encounter with Gordeau in the past.


Chaos is a young man with short unkept white hair, blue eyes and wears red-rimmed glasses. His attire consists of a dark grey turtleneck shirt, an unzipped greyish-blue jacket, light grey slacks with rolled up leggings, navy blue socks and greyish-blue and white sneakers. He carries with him a brown book with a bronze clasp called "Chaos Code", and wears a pendant that is a transparent cylinder with a silver serpent coiling around it.

His more casual clothing consists of a black-brown double-breasted peacoat over a white-high-collar shirt with pale-turquoise-pleaded pants.


Chaos appears to have a cool, calm and calculating attitude under normal circumstances. Being a general tactician, he tends to over-analyze even the simplest of situations and doesn't view himself as a strong warrior, and as such, hopes he doesn't run into any enemies that will pose a threat to him in battle. Despite this, he shown to be quite fearless, noted by Carmine and shown by Chaos when he confronted Merkava alone.

Despite being close to his friends, Chaos is also shown to be incredibly rude towards others at times and openly insults Hilda's intelligence and also takes a few potshots at other In-Births.

He tends to worry about Gordeau and his rather headstrong outlook to the point that Gordeau tends to tease him about it. Chaos also tends to be very superstitious and acts out on his own agenda without regard from anyone else (other than Gordeau and Hilda, of course).

Despite working for Amnesia, after Gordeau defects from the organization, Chaos secretly assists Gordeau from the shadows. It was said in his profile that Chaos was once a trouble-making delinquent, who used only brute force to fight until he redeemed himself and eventually resorts to intelligent-tactical combat.

Chaos has also been shown to be rather paranoid around certain people, such as when he says he'd much rather stay away from Uzuki and let Hilda do the talking, saying that he isn't entirely comfortable around people like her.

Even in his past as noted in Chronicle Mode before being first exposed to the Hollow Night, Chaos was very keen on the concepts of intellect, being someone who was willing to solve all sorts of mysteries of his own accord; this was even to the point of taking a silent leap of faith to see if he was able to become an In-Birth during his first time within the Hollow Night.

Chaos apparently has a fondness for thriller novels, which helped spark his curiosity regarding the Night.


According to Gordeau, Chaos was once a violent youngster. Gordeau has told Hilda that he has never beaten Chaos in a fight, but Chaos himself denies it - meaning that Chaos has at least once fought and lost to Gordeau. Chaos changed his style and started to fight using intelligence instead of brute force, which places him in his current position in Amnesia focusing more on intel.

Episode: The Sage Cometh In The Night (賢者は深き夜に)
Before he joined Amnesia officially, Chaos used to go solo on researching the mysterious rumors of the Hollow Night, which he initially believed to be merely foolish rabble. However, Chaos soon developed a curiosity for the Night after hearing in on conversations at the library. Chaos expresses his frustration on not being able to proceed on a report focusing on the Night and heads off to a bookstore to see if he can find anything else regarding the Night there. By the time Chaos leaves, night has already fallen and he finds himself suddenly overcome with a strange chill. When it wears off, Chaos notices the red-tinted mist in the suddenly heavy air and realizes that he has entered the Hollow Night and the sickness he felt earlier is from entering. Chaos decides to go and look around, which goes on for about an hour. After a while, Chaos comes across a group of Voids. He tries to run, but finds himself unable to move. Realizing that this is the only way to leave the Night, Chaos voluntarily lets the Voids attack him and collapses from the pain, not before swearing to uncover every mystery that the Night has to offer. Chaos awakes soon after this and decides to investigate the Hollow Night further.

After gaining some experience in the more minor nights that occurred afterwards, Chaos manages to hone his abilities to a rather weak yet plausible level and had a run in with a particularly violent In-Birth. However, he comes across two strange individuals who he learns are called Hilda and Gordeau. The one called Gordeau notices Chaos listening in on their conversation but calls bluff, sparing him from Hilda's wrath. After their mention of their planned "attack" on Licht Kreis, the two soon leave without spotting Chaos; Chaos soon decides that in order to gain the information on the Hollow Night that he himself wanted, he decides to use Amnesia's attack as a diversion to sneak into the Licht Kreis HQ to get what he is looking for.

Chaos was offered by Gordeau to join Amnesia, after gaining an ancient book known as the Chaos Code from an abandoned Licht Kreis library and escaping from a brief scuffle with the Licht Kreis Executor, Orie Ballardiae; Gordeau himself states that he was already well-aware of Chaos' presence, and decided to ask him to join out of the fact that they themselves were fairly disorganized and needed someone to help plan their operations more effectively. Despite Chaos not wanting to involve himself in such matters, Gordeau's charisma soon gets to Chaos and he then decides to join, and the two ended up being very close friends ever since.

Episode: Amnesia VS Bankikai (『忘却の螺旋』vs『万鬼会』)
After joining Amnesia, Chaos took control of operating behind the scenes. He rarely appeared before the other members and not many knew about him. Once during an operation Chaos personally appeared under the alias of "Bloody Chaos" and ever since people kept calling him by that nickname - Chaos personally doesn't like to be called by that name. At Gordeau's bar, Chaos briefs him, Hilda and Roger, another friend of Gordeau, on the details behind the new faction Bankikai and their upcoming battle with them. Chaos turns up with them but decides not to fight.

Episode: Festival Flames (祭りの後火)
After Roger turned into a fallen Void due to the presence of the Abyss and died at the hands of the Crimson Knight Erika Wagner, which caused Gordeau to leave Amnesia to hunt her down and make up for his past mistakes, Chaos devises a new rule to the rest of the members that only Hilda should be the only one who can obtain the power of Re-Birth, due to not only being a leader of Amnesia herself, it was also because her vessel happens to be strong enough to resist the Abyss’ influence.

Chaos also mentions that he has been studying a new recruit of Amnesia who called herself the "Black Monger" and took note of her unusually powerful abilities, He also states that he wouldn't really do well with people like her and tells Hilda that the two might get along well.

Episode: Chained Soul (魂縛の枷鎖)
At some point, Chaos somehow acquired the Eliminators without him knowing what the blades truly are until they were revealed upon first meeting Seth of the Night Blade. Wishing to co-operate with him peacefully, Chaos gave him the Eliminators in exchange for his services as an assassin.

Episode: Road To The Under Night...
Chaos goes to meet up with Hilda within the Altar of Light And Darkness, tired after getting everything prepared. The two have a brief chat before Hilda dismisses him.

Even after Gordeau left Amnesia, Chaos and he have been in contact and working together to track down the Licht Kreis and find the Crimson Knight responsible for killing Roger, instead of a mercy kill by Gordeau. Chaos personally is aiming to stand against Aion, Amnesia and the Licht Kreis with the allies he seeks to gain.


Chaos uses a book called The Codex of Disorder: Chaos Code (混沌の法典 (「ケイアス・コード」)) to command a lizard-shaped Void known as Azhi Dahaka (アジ・ダハーカ). The book was originally found by Chaos within a secret room at a headquarters building of Licht Kries, under Adelheit's protection. His ability is the "EXS of Illusion" (肖影のEXS): Umbral (アンブラル), which allows him to project and manifest certain objects, particularly books.

Beforehand in the chronicle mode, Chaos could only draw out a portion of its summoning power to summon a variety of beasts from various types of books that could only appear for a brief moment. It was due to this difficulty in managing his power beforehand that Chaos jokingly wished out of his chagrin that "he had the power to fire laser beams from his hands instead".

He also has some form of acrobatic combat prowess to compensate for times his powers are not available and for close-quarters combat, as well as a bit of photokinesis to augment his physical blows (he often focused on brute force before changing up his style to what it is now). Also beforehand in the chronicle mode, he was able to train himself to be able use some of his EXS for physical-mobility feats.

Musical Theme

Title Description
Erudite Eyes Chaos' theme
Cross Thought Gordeau VS Chaos theme

Title Description
The Scholarly Eye Chaos' theme
Crossed Thoughts Gordeau VS Chaos theme

Composer Commentary

Erudite Eyes
I'm expressing "calm and collected" and "unparalleled accuracy" from the intro until the refrain. During the refrain, "beast" and "chaos" are being expressed. Melody is rather simple, but chord progression moves pretty elusively. [2]

Cross Thought
An encounter. These two come across each other. I put that image into the intro.

The guitar in the first verse is captivating and comes out strongly, but the strings tremolo expresses the hidden feelings. The storm of two-five progression advances the story in the second verse. And then, everything is unleashed during the refrain.

The song is filled with melancholia to the utmost limit. [3]

Erudite Eyes
イントロからサビで「冷静沈着」と「正確無比」サビ終わりで「獣」と「混沌」を表現しています。 メロは割と単純なのですが、コード進行は結構掴みどころのない動きですね

Cross Thought



Introduction Text

He schemes. Staring down his opponents from behind his glasses. He keeps a beast within
and a book filled with nothing but chaos. He awaits the chance to unleash his power. The
desire to find his beloved friend and a comrade who tries to stop him. But which he was
going to pick was obvious... The beast shows its fangs, crushing anything it finds in its path.

He schemes. Staring down his opponents from behind his glasses. He keeps a beast within,
and a book filled with nothing but chaos. He awaits the chance to unleash his power. The
desire to find his beloved friend, and a comrade who tries to stop him. But which we was
going to pick was obvious... the beast shows its fangs, crushing anything it finds in its path.

He plots. Staring at the truth with his clear eyes over the glasses.
The beast within him, Chaos Code. Hiding and waiting for the chance to release the chain.
His dearest friend's wish. His delightful colleague had a conflicting ambition.
Which to choose is too obvious. The obedient beast bares the fangs.
They will equally bite off everyone who stands in his way.



Name Command
Unique Attacks
Code Reflect
→ + C
Unique Attack
Midair ↓ + C
Unique Attack
C > C
Unique Attack
B > B
Force Function
Snake Around
Simultaneously B + C
Special Attacks
Sidle up
Hold A or B or C
Air OK
That's the prey
↓↘→ + A or B or C
*EX Able
Breathe out
↓↙← + A or B or C
*EX Able
Repel them
→↓↘ + A or B or C
*EX Able
Hide away
↓↓ + A or B or C
Air OK *EX Able
Infinite Worth (Consumes 200% EXS)
Dissect Barrage
←↙↓↘→ + D
Infinite Worth EXS (Consumes 200% EXS)
Deep Revenance
A · B · C · D simultaneously
Usable when below 30% health

Check the details about Chaos' gameplay from here!


Official Art
Character Select
Victory Portrait
SD Character
Ed cha.png
Arcade Mode Ending
Ed gor.png
Arcade Mode Ending (Gordeau)
Chronicle Mode Event (The Sage Cometh In the Night)
Chronicle Mode Event (Amnesia Vs. Bankikai)
Normal (通常)
Happy (喜)
Angry (怒)
Sad (哀)
Comfort (楽)
Eyes Closed (目を閉じる)
Official Illustrations
Happy Birthday by 6sec (2013)
Happy Birthday by Seiichi Yoshihara (2014)
Happy Birthday by Yuusuke Nakahara (2015)
Happy Birthday by Satou (2016)
Happy Birthday by Kara Osawa (2017)
Chaos 2018.png
Happy Birthday by Takehiko Wagatsuma (2018)
Chaos 2019.png
Happy Birthday by Seiichi Yoshihara (2019)
Happy Birthday by Seiichi Yoshihara (2020)
Guest Illustrations
St guest05.png
By Yuki Sugiyama (UNIst)
Concept Art
Concept sprites from French Bread's Ustream
Concept art from Exe:Late[cl-r] gallery
Concept art from Exe:Late[cl-r] gallery
Concept art from Exe:Late[cl-r] gallery
Concept art from Exe:Late[cl-r] gallery
Store Icons
Character colors 4.jpg
Additional colors (Playstation Store)
Character colors 8.jpg
Additional colors 2 (Playstation Store)
Chaos system voice.jpg
System Voice (Playstation Store)
System voice all in one.jpg
System Voice all-in-one (Playstation Store)
Gameplay Tutorial for Exe:Late


  • The name of Chaos' beast, Azhi Dahaka, comes from a mythological evil figure who appears in Zoroastrianism. Azhi Dahaka was told to be three-headed and six-eyed dragon.
    • In the localized English text, Azhi Dahaka is spelled "Aji D'haka".
  • The katakana for his name is a unique way of writing "Chaos" in Japanese; Kaosu (カオス), Keeosu (ケーオス) and Keiosu (ケイオス) are the more common ways to write it in katakana. However, "Keiasu" may actually be a closer spelling to the Western order-writing of his real name ("Kei Asu"ma), which is possibly an alias chosen for himself during his direct encounter with Gordeau in the chronicle mode.
  • Both Chaos and Gordeau are the first two characters to gain a rivalry theme in the series.



Playable Characters
Guest Characters
Non-Playable Characters