Bryn2 This Servant is a Limited Servant Limited. They are only available during special summoning campaigns. When no such campaigns are active, this Servant cannot be summoned.
This article is for Class-Foreigner-Gold Mysterious Heroine XX. For 5★ Class-Assassin-Gold, see Mysterious Heroine X. For 5★ Class-Berserker-Gold, see Mysterious Heroine X (Alter).


Mysterious Heroine XX

★ ★ ★ ★

Japanese Name: 謎のヒロインXX
AKA: MHXX, Mysterious Heroine X (Foreigner)
ID: 222 Cost: 12
ATK: 1,625/9,751 HP: 1,800/11,250
Grail ATK: 11,806 Grail HP: 13,640
Voice Actor: Kawasumi Ayako Illustrator: BUNBUN
Attribute: Star Growth Curve: Reverse S
Critabsup Star Absorption: 147 Stargainup Star Generation: 15%
Npchargeup NP Charge ATK: 0.64% NPGainUpDmg NP Charge DEF: 3%
Instapowerup Death Rate: 10% Alignments: Lawful・Good
Gender: Female
Traits: Arthur, Brynhildr's Beloved, Dragon, Female, Humanoid, King, Riding, Saberface, Servant
Quickicon4  |  Artsicon3  |  Bustericon4  |  Extraicon4
Active Skills Passive Skills Noble Phantasm Ascension Skill Upgrade
Stats Bond Level Biography Trivia Images

Active Skills

Available from the start
Piloting EX
Invincible Grants self Invincibility for 1 turn.
Increases own attack for 1 turn.
Level 12345678910
Attackup Attack + 30% 32% 34% 36% 38% 40% 42% 44% 46% 50%
Cooldown 7 65

Unlocks after 1st Ascension
Detective's Instinct E
Gain critical stars.
Reduces own critical star absorption for 1 turn.
Level 12345678910
GainStars Stars + 10 11 12 13 14 15 16 17 18 20
Starabsoprtdown Absorption - 50% 55% 60% 65% 70% 75% 80% 85% 90% 100%
Cooldown 6 54

Unlocks after 3rd Ascension
Justice from the Ends of the World A
Invinciblepierce Ignores Invincibility for 1 turn.
Charges own NP gauge.
Increases own damage against Threat to Humanity enemies for 1 turn.
Level 12345678910
NpCharge NP + 20% 21% 22% 23% 24% 25% 26% 27% 28% 30%
Powerup Threat to Humanity Damage + 30% 32% 34% 36% 38% 40% 42% 44% 46% 50%
Cooldown 7 65

Passive Skills

Existence Outside the Domain D
Stargainturn Gains 2 critical stars every turn.
Resistanceup Increases own debuff resistance by 4%.
Cosmo Reactor B
Stargainup Increases own critical star generation rate by 8%.
Independent action
Independent Action A
Critdmgup Increases own critical damage by 10%.
Riding A
Quickupstatus Increases own Quick performance by 10%.

Noble Phantasm

Double X DynamicRegulation of the Aether​ Cosmos
Sapphire Galaxy Id Est Cosmos
Rank Classification Type Hit-Count
EX Anti-Unit Arts 4
Effect Deals damage to one enemy.
Powerup Deals 150% extra damage to Class-Saber-Gold Saber class Servants.
NP Level 1 2 3 4 5
Powerup Damage + 900% 1200% 1300% 1425% 1500%
Overcharge Effect Increases own attack for 1 turn. (Activates first)
Charge 100% 200% 300% 400% 500%
Attackup Attack + 20% 30% 40% 50% 60%

謎のヒロインXX 蒼輝銀河即ちコスモス

謎のヒロインXX 蒼輝銀河即ちコスモス


Item 1 Item 2 Item 3 Item 4 QP
1st Dragon fang8 Infinity gear8 QPicon50,000
2nd Blacktallow8 Medal of Great Knight8 QPicon150,000
3rd Bloodtear8 Giant's Ring8 QPicon500,000
4th Dragons reverse scale8 Primordial Lanugo8 QPicon1,500,000

Skill Reinforcement

Item 1 Item 2 Item 3 Item 4 QP
1st Heros proof8 QPicon100,000
2nd Dragon fang8 QPicon200,000
3rd Infinity gear10 QPicon600,000
4th Medal of Great Knight10 QPicon800,000
5th Aurora Steel10 QPicon2,000,000
6th Giant's Ring12 QPicon2,500,000
7th Primordial Lanugo12 QPicon5,000,000
8th Dragons reverse scale12 QPicon6,000,000
9th Crystallized lore1 QPicon10,000,000


Strength: B
Endurance: B
Agility: B
Mana: E
Luck: D

Bond Level

Bond Level 1 BoundLevel1 2 BoundLevel2 3 BoundLevel3 4 BoundLevel4 5 BoundLevel5 6 BoundLevel6 7 BoundLevel7 8 BoundLevel8 9 BoundLevel9 10 BoundLevel10
Bond Required 3,000 6,125 6,125 6,125 6,125 262,500 290,000 300,500 309,500 315,500
Total Bond 3,000 9,125 15,250 21,375 27,500 290,000 580,000 880,500 1,190,000 1,505,500
Bond 10 Reward CE0892Icon Memories of the Earth
When equipped on Mysterious Heroine XX,
Increases Party’s damage to Class-Saber-Gold Saber class enemies by 20% while she is on the field.
Chaldean Visionary Flames [?]
11 BoundLevel1 12 BoundLevel2 13 BoundLevel3 14 BoundLevel4 15 BoundLevel5
1,090,000 1,230,000 1,360,000 1,500,000 1,640,000
2,595,500 3,825,500 5,185,500 6,685,500 8,325,500


Unlock Description Translation
Default サーヴァント・フェスティバルを破壊する為に



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―――?

Bond 1 身長/体重:154cm・48kg

属性:秩序・善   性別:女性

Height/Weight: 154cm・48kg

Source: Cosmo Guardian Trilogy
Region: Servant Universe
Alignment: Lawful・Good
Gender: Female
*her measurements change when she Enplanes.
"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!"

Bond 2 『蒼輝銀河即ちコスモス』

ランク:EX 種別:対人宝具 


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.

Bond 3 『無銘星雲剣』

ランク:EX 種別:対軍宝具



Nameless Nebula Sword

Rank: EX
Type: Anti-Army
Range: 9~99

Mumei-Seiunken. 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.

Bond 4 乗着:EX



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.

Bond 5 謎のヒロインXは、一言でいうとコメディドラマの主人公である。



     ―CG第1部 ストーリーより抜粋―

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 -

Requires Bond Level 5
Extra コスモ刑事になったXは「これはいい機会ですね」と名前・戸籍をXXと改名。




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.


Mysterious Heroine XX was available for summoning during the:

Servant Summer Festival! 2018 Servant Summer Festival! 2018 Rerun


  • Mysterious Heroine XX is the first and only 4★ Foreigner.
  • Mysterious Heroine XX's Noble Phantasm is also known as Twin-Myniad Disaster and Double X Dynamic.
  • She shares the exact HP values at both minimum and maximum with Martha (Ruler).
  • She is the first and only Foreigner not associated with a Lovecraftian horror.


Community content is available under CC-BY-SA unless otherwise noted.