Mysterious Heroine XX

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This article is about the limited 4★ Foreigner Mysterious Heroine X. See also:

Mysterious Heroine XX Icon Star.png
1,625 - 9,751 (11,806)
1,800 - 11,250 (13,640)
Star Absorption
Star Generation
NP Charge Attack
NP Charge Defense
Death Rate
Growth Curve
Semi S
Chaotic Good
Available for summon during Servant Summer Festival.

Traits: Servant, Humanoid, Arthur, Dragon, Riding, Altria Face, King, Knight, Not Weak to Enuma Elish, Ally of Justice, Under 165cm, Loved One, Female, Chaotic Good
Also Known As: MHXX

Number of Hits: Icon quick.png 4 | Icon arts.png 3 | Icon Buster.png 4 | Icon extra.png 4


Active Skills

Starts with this Skill

Suit Up EX
乗着 EX
Skill Icon Invul.png
  • Increase your ATK. (1 turn)
  • Apply Invincible to yourself. (1 turn)

Targets: Self
Cooldown: 7 / 6 / 5

Level 1 2 3 4 5 6 7 8 9 10
Attack+ 30% 32% 34% 36% 38% 40% 42% 44% 46% 50%
Icon Servant 222.png

Unlocks at 1st Ascension

Police Instincts E
刑事の直感 E
Skill Icon CStar Gain.png
  • Gain Critical Stars.
  • Reduce your Critical Star Gather Rate. (1 turn)

Targets: Self
Cooldown: 6 / 5 / 4

Level 1 2 3 4 5 6 7 8 9 10
Stars+ 10 11 12 13 14 15 16 17 18 20
Star Gather - 50% 55% 60% 65% 70% 75% 80% 85% 90% 100%
Icon Servant 222.png

Unlocks at 3rd Ascension

Justice of World's End A
最果ての正義 A
Skill Icon Invul Pierce.png
  • Increase your NP Gauge.
  • Apply Ignore Invincible to yourself. (1 turn)

Targets: Self
Cooldown: 7 / 6 / 5

Level 1 2 3 4 5 6 7 8 9 10
NP Charge+ 20% 21% 22% 23% 24% 25% 26% 27% 28% 30%
Attack + 30% 32% 34% 36% 38% 40% 42% 44% 46% 50%
Icon Servant 222.png

Passive Skills

Entity of the Outer Realm D
Skill Icon Foriegner.png
Gain 2 Critical Stars at the end of every turn.
Increase your Debuff Resist by 4%.

Cosmo Reactor B
Skill Icon CStar Drop Up.png
Increase your Critical Star Drop Rate by 8%.

Independent Action A
Skill Icon Independent Action.png
Increase your Critical Strength by 10%

Riding A
Skill Icon Riding.png
Increase your Quick Card effectiveness by 10%

Append Skills

Extra Attack Boost
Skill Icon Damage Up.png
Increase Extra Attack Card's effectiveness for yourself.
Level 1 2 3 4 5 6 7 8 9 10
Extra+ 30% 32% 34% 36% 38% 40% 42% 44% 46% 50%

Mana Loading
Skill Icon NP Charge.png
Begin battle with NP charged for yourself.
Level 1 2 3 4 5 6 7 8 9 10
NP Gauge+ 10% 11% 12% 13% 14% 15% 16% 17% 18% 20%

Anti-Moon Cancer (ATK Up)
Skill Icon Attack Up.png
Increase ATK against [Moon Cancer] class for yourself
Level 1 2 3 4 5 6 7 8 9 10
ATK+ 20% 21% 22% 23% 24% 25% 26% 27% 28% 30%


Noble Phantasm

Etherspace, Yet Lawful
Sapphire Galaxy, in Other Words Cosmos EX

Command Card Arts.png
  • Deal significant damage to one enemy
  • Additional 150% Special Attack damage to SaberSaber Class Servants
  • Overcharge: Increase your ATK (1 turn) *Activates First

Targets: One Enemy
Type: Anti-Personnel
Hits: 4

Level 1 2 3 4 5
Damage 900% 1200% 1350% 1425% 1500%
Overcharge 100% 200% 300% 400% 500%
Attack Up 20% 30% 40% 50% 60%

Upgrades after Rank Up 1. Released during Imaginary Scramble Pre-Release Campaign.

Etherspace, Yet Lawful
Sapphire Galaxy, in Other Words Cosmos EX

Command Card Arts.png
  • Deal significant damage to one enemy
  • Additional 200% Special Attack damage to SaberSaber Class Servants
  • Overcharge: Increase your ATK (1 turn) *Activates First

Targets: One Enemy
Type: Anti-Personnel
Hits: 4

Level 1 2 3 4 5
Damage 1200% 1500% 1650% 1725% 1800%
Overcharge 100% 200% 300% 400% 500%
Attack Up 20% 30% 40% 50% 60%

Material Requirements


Level 1st Ascension 2nd Ascension 3rd Ascension 4th Ascension
Icon Item Dragon Fang.png8
Icon Item Eternal Gear.png8
Icon Item Black Beast Grease.png8
Icon Item Great Knight Medal.png8
Icon Item Tearstone of Blood.png8
Icon Item Giant's Ring.png8
Icon Item Dragon's Reverse Scale.png8
Icon Item Primordial Lanugo.png8
QP 50,000 150,000 500,000 1,500,000

Skill Reinforcement

Level 2 3 4 5 6 7 8 9 10
Icon Item Proof of Hero.png8
Icon Item Dragon Fang.png8
Icon Item Eternal Gear.png10
Icon Item Great Knight Medal.png10
Icon Item Aurora Steel.png10
Icon Item Giant's Ring.png12
Icon Item Primordial Lanugo.png12
Icon Item Dragon's Reverse Scale.png12
Icon Item Crystallized Lore.png
QP 100,000 200,000 600,000 800,000 2,000,000 2,500,000 5,000,000 6,000,000 10,000,000

Append Skills

Level Unlock 2 3 4 5 6 7 8 9 10
Icon Item Mysterious Heroine XX Coin.png120
Icon Item Octuplet Crystals.png8
Icon Item Fool's Chain.png8
Icon Item Claw of Chaos.png10
Icon Item Black Beast Grease.png10
Icon Item Mystic Spinal Fluid.png10
Icon Item Mystic Gunpowder.png12
Icon Item Reactor Core of Dawn.png12
Icon Item Fragment of a Twinkling Star.png12
Icon Item Crystallized Lore.png


Noble Phantasm


Bond Level

Bond Level 1 2 3 4 5 6 7 8 9 10
Bond Required 3,000 6,125 6,125 6,125 6,125 262,500 290,000 300,500 309,500 315,000
Total Bond 3,000 9,125 15,250 21,375 27,500 290,000 580,000 880,500 1,190,000 1,505,000
Bond 10 Reward Icon CE 0892.png Memories of Earth
When equipped on Mysterious Heroine XX,
Increase ATK against [Saber] for all allies by 20% while she's on the field.
Icon Item Lantern of Chaldea.png
Lantern of Chaldea allows you to unlock Bond Level 11 through 15 for the chosen Servant.
Bond Level 11 12 13 14 15
Bond Required 1,090,000 1,230,000 1,360,000 1,500,000 1,640,000
Total Bond 2,595,000 3,825,000 5,185,000 6,685,000 8,325,000



A single shooting star that arrived to destroy the Servant Festival.
She is the voice of Space Law, and a merciless Machine Servant tasked with obliterating all of Earth's humans and Foreigners.
And when her unexpected identity is finally revealed, rumor is that the shock may overwhelm everyone!


Height: 154cm
Weight: 42kg
Origin: The Cosmo Guardian Trilogy
Region: The Servant Universe
Alignment: Chaotic Good
Gender: Female
*Height and weight changes every time she suits up or purges her armor.
"My weight is just high because of my work stress. I'll get back to my original 42kg real quick!"


『Etherspace, Yet Lawful』
Rank: EX
NP Type: Anti-Personnel
Range: 9 - 99

The Servant Universe Is the Cosmos.
Depending on her mood, she will shout either "Twinmyniad Disaster" or "Double X Dynamic," but this Noble Phantasm's True Name is "Etherspace, Yet Lawful." The True Name represents and mirrors the Rhongomyniad that protects the laws of space. The Rhongomyniad LR's safety limiters are removed, and it devastates Sabers by increasing its output. It'll blow its target up, planet and all.

She rejects the notion of a right to remain silent or a right to an attorney, because she is the voice of judgment. This is a useful Noble Phantasm that is not only a Special Attack against Foreigners, but also against Sabers.


『Nameless Nebula Sword, Secretmyniad』
Rank: EX
NP Type: Anti-Army
Range: 9 - 99

A galaxy nebula slicer that uses Rhongomyniad LR, a weapon said to be space's balancing scales. Swinging the spear around radiates light like a swirling nebula, which mows down all around it, friend or foe. This doesn't really get used in FGO.

Justice of World's End: A
Power from the boundary, the most advanced and furthermost area of space. It tears away at nothingness, and is the true principle behind expanding space. It offers all but unlimited power, able even to repel even higher beings from outside the universe in order to restore balance to the universe. XX...doesn't really understand how it works.


Suit Up: EX
The protection of the sacred spear armor Aahvalon. The armor constantly exists around XX in the form of spiritrons. With a speed of negative one second (where it can turn back time by one second to activate even if XX is taken by surprise) it protects and arms XX. She calls this little stunt "Suiting Up."

...Don't kid yourself, missy. This is actually an astonishing skill that XX acquired because she habitually overslept and was late for everything, even after joining the Galactic Police. It could actually be called a quick change skill. In fact, there's no real need for it, and it functions as armor in its spiritron state just fine. Arming oneself significantly increases their attack.

Police Instincts: E
Divine revelation used to find culprits. The low rank suggests it's really not so great for solving crimes, though. Various hints to solving crime seem to stem from otherworldly inspiration completely devoid of logic. XX never really notices these hints though. In some cases, this demerit becomes advantageous, actually making this a brilliant skill.


To sum up Mysterious Heroine X in a sentence would probably be simplest by saying that she is the protagonist of a TV comedy. By inheriting Altria's serious demeanor, X focuses on doing everything as quickly and simply as possible. Contrary to her polite and energetic mannerisms, she is extremely competitive (since she's not really aware of this, she is unbelievably dense). She challenged herself to achieve various things, and was absolutely relentless, not giving up until she succeeded. This was a bit problematic, but since she possesses such a virtuous nature, she ended up working to benefit others, so it all worked out okay.

With the Servant Universe full and boiling over with an excess of Extra Classes, the balance between heroes and villains collapsed. The moment the scales of space tilted toward the villains, XX vowed to change her principles... And then the show headed into a new season. As an unemployed X didn't know what to do, she was hired by a secret society, the Galactic Police. In their HQ's center. she stumbles onto the oldest artifact in space, the Rhongomyniad. Her talents are acknowledged, and she becomes active as a Galaxian.

-Story Excerpt from CG Episode I-

Clear Bond Level 5

When X became a member of the Galactic Police, she saw this as a good opportunity and changed her name and registration to XX. As she gained a new identity, she was able to abandon all her past debts, and she established Special Investigation Division O that cracked down on Foreigners, the invaders from outside space. And so was born XX, huntress of the wicked.

Her whole Saber-hunter thing has kind of faded, and now she's a Foreigner-hunter. Still, her desire to eradicate all Sabers hasn't gone away, so she still has her Saber special attacks.

Motivation, Behavior Towards Master:
Partner on Earth. A reliable wallet.

Since X has zero skills and awareness when it comes to romance, Master is more of a friend to her. Eventually, though, she realizes they are someone special.

"What's this sensation I'm feeling in my chest...don't tell me there's a wicked Saber on this planet!?"

Her erroneous thinking leads her to miss her opportunity. She's pretty much the same X, but she's aware that she's an officer, so tries to act more mature. Since she's a few versions later (read: older) than X, she looks like an office worker worn out by the daily grind.



















     ―CG第1部 ストーリーより抜粋―

Extra: Requires Bond Level 5






A single meteor that came to destroy the Servant Festival.
A delegate of the laws of the universe, she eradicates Earth's mankind and the Foreigners who shares the same attributes as herself.
A peerlessly ruthless Machine Servant.

It has been said that, when her unexpected true face is revealed, anyone will avert their gaze due to extreme astonishment―――?


Height: 154cm
Weight: 42kg
Origin: The Cosmo Guardian Trilogy
Region: The Servant Universe
Alignment: Chaotic Good
Gender: Female
"The weight has just increased a little due to the stress of daily hard work, but I will return to my previous 42kg in no time!"


Sapphire Galaxy Id Est Cosmos
Rank: EX
Type: Anti-Unit
Range: 9~99

Regulation of the Aether​ Cosmos.
Although she shouts many things in accordance with her mood at the time - such as "Twin-Mynyad Disaster" or "Double X Dynamic" - its True Name is "Ether Universe, Howbeit the Order".
By means of opposing mirrors, this True Name denotes the rules of the universe that Rhongomynyad protects. A dynamic Saber Slash performed after releasing the safe-mode of Rhongomynyad-LR and increasing its output.
It explodes the opponent along with the planet itself.
The final ruling measure, which does not adhere to things such as the right to remain silent or the right to call a lawyer.
A convenient Noble Phantasm that is endowed with special effectiveness not only against Foreigners, but also against the Sabers.


Nameless Nebula Sword
Rank: EX
Type: Anti-Army
Range: 9~99

Mumei-Unken. Himitsu-Mynyad.
A Galaxy Nebula Slash that employs Rhongomynyad-LR, which is said to be the balance of the universe.
By swinging the spear round-and-round, its beam of light will swirl like a nebula and mow down everything in the surroundings. It makes no distinction between friends and foes.
Fundamentally not employed in FGO.

Justice from the Ends of the World: A
A power from the "boundary" that is both the far beyond and the forefront of the universe. Also, a power to rip apart "nothingness" and the very truth that expands the universe.
A powah that "keeps the balance of the universe" and drives away even the superior existences from a different universe, but XX herself does not quite understand it.


○Riding: EX
A divine protection from the Holy Spear Armor Avalon. The armor constantly exists around XX as spirit particles.
She call the quick work of materializing・arming this at a speed of minus one second (even when suffering a surprise attack, she goes back in time one second before it happens and equips this) "Enplane".
Right out.
A fearsome skill acquired by XX, who is recurrently late for work due oversleep despite becoming a Cosmic Sheriff. Surely, this is just a skill for changing clothes.
As a matter of fact, its functions as an armor are displayed even in a spirit particles-state, so there is really no need to materialize it.
Once armed, her offensive abilities increase dramatically.

○Detective's Instinct: E
A divine revelation for the sake of pinning down a criminal.
At this rank, it is better not to use it to solve crimes.
By means of a higher dimensional insight that ignores reason, hints for the sake of solving a crime are spread across the surroundings - but XX herself does not notice those hints no matter what.
This is actually quite an excellent skill that can turn demerits into merits.


To put it simply, Mysterious Heroine X is the protagonist of a comedy-drama.
Since she is basically Miss Artoria without her serious components, X behaves in the shortest・fastest・simplest manner regarding anything.
Contrary to her energetic, polite conduct, she has a hopeless personality that hates to lose (due being unaware of this herself, her inability to read the mood is staggering), challenges pretty much
everything and does not give up until she wins.
Still, since she "ultimately ends up working for the sake of those around her" due being good person by nature, things functioned well at the end of the day.

The Servant Universe came to a standstill and the proportion of heroes and villains crumbled due the excessive issue of Extra Classes.
When the balance of the universe tilted towards the villains, X renewed her convictions.
In more specific terms, the program embarked on a new season.
Worried about being unemployment, X got herself a job on the secret society・Galaxy Police and coincidentally caught Rhongomynyad, the oldest artefact in the universe that was lying dormant at its centre.
Having her talents recognized, she began to play an active role as a space sentinel (Galaxian).

- extract from the 1st part of CG's story -

Clear Bond Level 5

Upon becoming a Cosmic Sheriff, X thought "this is a good opportunity" and changed her name・family register​ to XX.
By becoming a new person, she defaulted all debts incurred so far and established the Division 0 of Special Investigations, which cracks down on invaders from outer space - the Foreigners.
The birth of the Evil Deity Hunter, XX.

Her instinct as a Saber Hunter became dim, while her instinct as a Foreigner Hunter came to prominence.
That being said, it is not like she quit her Saber elimination movement, so the special effectiveness against Sabers remains the same as always.

○Motivations・Attitude towards the Master
Her partner on Earth. A reliable wallet.
Since X has pretty much zero romance skill, she just treats him as a friend. Still, she will eventually notice that he is her precious someone and then let her chances slip up due some misunderstanding.
"What is this feeling in my chest... could it be that a Saber evil deity came to this planet!?"
Fundamentally, she is the same as X. But due the self-awareness as a sheriff increasing her consciousness, she behaves more like an older sister than X.

Since she belongs to a series from a few years later than X, she is like an office lady who became tired of daily life.

Featured in the Following Craft Essences

Icon CE 1066.png

Featured in the Following Stories