Mary Sioux

Vol 3 Ch 5 Pg 279 Bad scan LQ



Character Name
Full Name Mary Sioux
Other Name Mary Sue
Kana メアリー・スー
Personal Info

14 [1]
13 [2]
12 [3]

Gender Female
Weapons & Equipments
  • Rifle
  • US Flying Gear
  • US Orb
Military Info
Military Rank

Second Lieutenant [4]
Warrant Officer [5]
Private First Class [6]

Novel Chapter 4 The Devil in the Coast of Norden (Vol. 2)
Manga Chapter 22
Mary Sioux[7] or Mary Sue[8] is one of the main antagonists of the series, the ultimate rival and the tool used by Being X to counterbalance Tanya Degurechaff in the war. She is the sole daughter of Anson Sioux and his wife who hail from the Unified States.

Appearance Edit

In the anime, Mary is a young girl with long brown hair with curled ends and green eyes. When she was still an ordinary citizen, she was seen wearing a blouse with long skirt.

In the light novel, she has straight and longer brown hair, her eyes were greenish blue. As a volunteered soldier, she is seen wearing an US military uniform.

Personality Edit

When she was a citizen, she was a caring and loving girl. She loved her father very much.

After her father's death, she became rather more vengeful and serious. Her hatred grows whenever she hears the name "Devil of the Rhine", she will begin to rage but resulting exposing herself in an out of control state.

Plot Edit

Past Edit

Mary lived in a quite, simple and average life with her mother. Sometimes, she had slight struggles without her father, which left her side to become a soldier to benefit her country.

Battle of the Fjord/Plus Ultra; Chapter IV: The devil in the coast of Norden Edit

Before the Christmas in 1924, Mary bought a state-of-the-art submachine gun for Anson as an early Christmas present. The novel and manga revealed that she received it from an agent by the name of John who was working for the Allied Kingdom. The gift soon was stolen and kept by Tanya during the battle of Fjord.

How to use a Victory/The Finest Hour; Chapter V: Internal affairs Edit

After Mary learned about his father's fate in her grandmother's house in Arkansas, she volunteered to become a soldier to take revenge on the Devil of the Rhine even though she was below the minimum age for volunteer soldiers. At that moment, she prayed to the God and received the same blessing as Tanya from Being X.

Abilities Edit

Prayer/Blessing/Gospel Magic

The user can cast a spell by praying to Being X stronger than Tanya's powers. The speed is faster than an average human. Also, the firing abilities exceeds to Tanya's capabilities with 100% exact hit to the target.

She can blow a whole battalion (48 men) with only one artillery spell, as opposed to Tanya's, which can only wipe out a whole company (12 men). However it reduces her mana to fifty percent of her full power, as shown during her first mission as a volunteered soldier of US.

Rage Mode

The user's hatred and grudge to "Devil of the Rhine" becomes the source of the power. It exceeds the limits of Blessed User. The operation orb of the user becomes brighter and regenerates mana quickly.

However, as a side effect, the user loses control of their own movements and reason.

Quotes Edit

Catchphrase : "Curse you, Devil of the Rhine!"

(Mary's declaration [Episode 12]) : "I declare that for the sake of the peace I must protect and for the sake of the family I love, I will give my whole power! To make a world that no one else has to experience the sadness of losing their family to the Empire. And to enact God's justice! I swear by my good heart which believes in the Lord! May the Lord's grace be with me!"

(Mary to Tanya) : "I finally found you! Devil of the Rhine!"

Trivia Edit

  • Her name "Mary Sioux" or "Mary Sue" comes from the trope Mary Sue. However, because her character was rewritten when Youjo Senki became a light novel, she doesn't fit the trope very well anymore.
  • She is the only person who can match Tanya von Degurechaff in many battles.


  1. LN: Dabit deus his quoque finem Chapter IV Reorganization
  2. LN: Finest Hours Chapter 1 Open Sesame
  3. LN: Plus Ultra Chaper IV The Devil In The Coast Of Norden; Anime: Episode 7 Battle of Fjord
  4. LN: In omnia paratus Chapter IV: Encounter and Engage
  5. LN: Ut sementem feceris, ita metes Chapter V: Turning point
  6. LN: Abyssus abyssum invocat Chapter II Strange Friendship
  7. The spelling used by Crunchyroll, the anime's official English licenser.
  8. The spelling used by the official Japanese website.

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.