Shadow Border

Shadow Border

The Imaginary Numbers Submersible Shadow Border (虚数潜航艇 シャドウ・ボーダー, Kyosu Senkō-tei Shadō Bōdā?) is a vehicle which is used by the survivors of Chaldea in Fate/Grand Order: Cosmos in the Lostbelt.[1]


The Shadow Border is a twelve-wheeled armored vehicle capable of diving into Imaginary Number Space, which functions as a mobile base-of-operations for the survivors of Chaldea.[1][2]

The Shadow Border utilizes an "artificial Servant", namely a younger back-up of Leonardo da Vinci, as a navigator and pilot.[1] When operating in this capacity, Da Vinci resides in a pod in the computing room and is aware of anything occurring within the vehicle.[2]

Due to its intended purpose and the dangers it might face, the Shadow Border possesses considerable defensive capabilities. The vehicle's outer armor is fortified with modern technology and conceptual magecraft, such that normal weaponry shouldn't damage it.[3] It also has both optical and conceptual camouflage to conceal itself.[2] Its inner shell consists of multiple barriers stacked one on top of the other. With Da Vinci having worked together with Paracelsus and Nitocris to strengthen the barriers, they are apparently equal even to barriers from the Age of Gods, nearing the capability of a fortress made from divine steel.[4]

The Shadow Border doesn't possess external weapons, but it has an electromagnetic catapult on its deck to launch certain individuals, such as the Ortenaus-equipped Mash Kyrielight, into battle.[5]

Paper MoonEdit

The Shadow Border is equipped with the Imaginary Numbers Observation Device Paper Moon (虚数観測機 ペーパームーン, Kyosū Kansoku-ki Pēpā Mūn)?), which is used to facilitate dives into imaginary number space and to monitor both imaginary and real space.[1][2] It can display maps in the form of a rotating cylindrical projection similar to a drum roll, and can detect abnormal regions where the world's Texture is different, such as the Lostbelts.[2] The device itself is of a size and weight capable of being handled by an individual.[4]

Usage of the Paper Moon apparently requires authorization from Atlas, and details concerning its operation are contained in the TRI-HERMES records.[1]

Zero SailEdit

Zero Sail

'Zero Sail' dive into Imaginary Number Space

The Shadow Border's primary capability, Zero Sail: Imaginary Number Dive (虚数潜航ゼロセイル, Kyosū SenkōZero Seiru?), is a form of travel devised in the early stages of Chaldea's formation but abandoned due to difficulty and inherent danger.[1]

Taking the opposite approach to rayshifting, where a subject is broken down into Spiritrons and projected to a specific space-time belt, this method involves slipping between the gaps of the world and vanishing from reality, submerging the vessel into Imaginary Number Space (虚数空間, Kyosū Kūkan?), alternatively referred to as Minus Reality, the Seas of Time (時の海, Toki no Umi?) or the Sea of Imaginary Numbers (虚数の海, Kyosū no Umi?).[1]

The Zero Sail procedure begins with the Paper Moon being deployed and any destinations being set. Logical expressions (論理術式, Ronri Jutsu-shiki?) are then deployed over the Shadow Border’s external armor and the proof of existence (存在証明, Sonzai Shōmei?) attaching it to Real Numbers Space (実数空間, Jitsusū Kūkan?) is detached. A future prediction (未来予測, Mirai Yosoku?) is carried out for proof of hypothesis (仮説証明, Kasetsu Shōmei?) at the boundary surface (境界面, Kyōkai-men?) and space-time friction decompression (時空摩擦減圧, Jikū Masatsu Genatsu?) is mitigated. Once the departure procedures and any emergency procedures are completed, the Shadow Border departs from reality (現実退去, Genjitsu Taikyo?) and dives into the Sea of Imaginary Numbers.[1][3]

In order to resurface after submerging into Imaginary Number Space, it is necessary to form a connection with an entity in normal space, with the bond acting as an anchor.[2]


  • Control Room
  • Master's Room
  • Treatment Room
  • Workshop
  • Cell

The interior of the Shadow Border is larger than the exterior dimensions through the application of spatial distortion, allowing twice as much room in the internal space than normally possible and making it a barely livable habitat. Rooms in the Shadow Border include:[2]

  • Cockpit (操縦席コクピット, Sōjū sekiKokupitto?): The cockpit also acts as the Shadow Border's Command Center (司令室, Shirei-shitsu?).[2]
  • Master's Room: Ritsuka Fujimaru's quarters (also known as My Room (マイルーム, Mairūmu?)).[2]
  • Treatment Room (治療室, Chiryō-shitsu?): As Mash requires maintenance as a Demi-Servant, the infirmary has become her private quarters.[2]
  • Chaldea Staff Room (カルデアスタッフの部屋, Karudeasutaffu no Heya?): Due to space constraints, the surviving Chaldea staff members have been forced to bunk up to four to a room.[2]
  • Captain's Room (船長室, Senchō-shitsu?): Goldolf Musik has occupied the captain's chambers.[2]
  • Computer Room (電算室, Densan-shitsu?): Da Vinci often resides in a capsule in this room.[2]
  • Workshop (工房, Kōbō?): Sherlock Holmes has made his home in the workshop.[2]
  • Air-conditioning Control Room (空調制御室, Kūchō seigyo-shitsu?), Warehouse (倉庫, Sōko?), Arsenal (武器庫, Buki-ko?): Goldolf has restricted access to these areas.[2]
  • Shower[2]
  • Cell[3]


The Shadow Border is crewed by the survivors of Chaldea following the attack on the main facility by forces from the Lostbelts.[1]


Fate/Grand Order: Epic of RemnantEdit

Moonlight Lostroom - Holmes and Shadow Border

Holmes and the Shadow Border

The Shadow Border was constructed in secret in anticipation of certain enemies that might arise following the restoration of the world in the wake of the Human Order Incineration Incident, concealed within a container normally used for waste disposal. Holmes had also familiarized himself with the operation of the Paper Moon system through looking at the TRI-HERMES records.[1]

Fate/Grand Order: Cosmos in the LostbeltEdit

Second PrologueEdit

  • Shadow Border emerging from the container
  • Descending light

During the assault on Chaldea by forces from the Lostbelts, the survivors used the vehicle in conjunction with the waste container ejection system to escape from the facility. Driving through Antarctica, they then witnessed several lights descending abnormally from the sky, accompanied by Kirschtaria Wodime's declaration.[1]

Faced with the troops waiting at the coast, Holmes decided to deploy the Paper Moon in order to escape, despite the chance of the system working properly being less than 30%, recognizing it as a necessary step in order to overcome their enemy in the future. The Shadow Border then dove into Imaginary Number Space.[1]

Anastasia: Permafrost EmpireEdit

After a week in Imaginary Number Space, with supplies running low and tidal conditions giving them a narrow window of opportunity, the Shadow Border was forced to surface, using the Oprichniki to form a connection back to the changed world and surfacing within the Russian Lostbelt, with three months having passed in the world since their departure. While surfacing, the Shadow Border sustained damage which prevented it from diving again until repairs could be made.[6][2]

Götterdämmerung: Eternal Ice-Flame CenturyEdit

Shortly after departing the collapsing Russian Lostbelt, the Shadow Border was attacked by Kirei Kotomine, who succeeded in retrieving the imprisoned Kadoc Zemlupus. After a long journey towards the North Atlantic from Russia, the Shadow Border performed a brief dive to enter the Norse Lostbelt, having to transit the Lostbelt in order to reach the intended destination; the Wandering Sea.[3] During the dive, an unknown presence was detected in the craft's vicinity.[7] Not long after the Shadow Border's arrival in the Lostbelt, the craft was attacked by Sigurd-Surtr, who breached the hull and nearly killed the crew before leaving, having succeeded in seizing the Paper Moon.[4]

SIN: Land of Unified KnowledgeEdit

Shadow Border captured

Shadow Border captured and held hostage by Qin

Yuga Kshetra: The Black Final GodEdit

Olympus: Interstellar Mountain CityEdit

  • The Nautilus formed around the Shadow Border
  • The Nautilus/Shadow Border diving through Imaginary Number Space


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Fate/Grand Order: Cosmos in the Lostbelt Prologue
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 1
  3. 3.0 3.1 3.2 3.3 Fate/Grand Order: Cosmos in the Lostbelt - Götterdämmerung: Eternal Ice-Flame Century, Prologue
  4. 4.0 4.1 4.2 Fate/Grand Order: Cosmos in the Lostbelt - Götterdämmerung: Eternal Ice-Flame Century, Chapter 2
  5. Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 21
  6. Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Prologue
  7. Fate/Grand Order: Cosmos in the Lostbelt - Götterdämmerung: Eternal Ice-Flame Century, Chapter 1
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