Zena Marientail is a magic soldier belonging to Seryuu city's territorial army, her lineage is of the Chevalier Marientail house where her family are retainers of Earl Seryuu. She has a younger brother; Yukel Marientail, who is currently the family head. Though her family are nobles, they are of the lowest rank, with humble riches and lacking status in governmental politics. Zena's an adept wind user and evaluated to have a promising future as a soldier.
Zena has a slender body, azure eyes with her long straight bob hair. Her light-golden hair was woven into a braid. She's considered a 'charmingly beautiful girl' and 'plainly cute'. Her friend often teased her as flat-chested.
Whilst trying to complete her duty as a magic soldier of Seryuu city's territorial army, when the greater demon attacks Earl Seryuu's castle; Zena is attacked and thrust away crashing into a tree. Satou rescues and takes her to a medical station when he finds her dangling in the tree. Her encounter would further cement her wish to fly, as she marvels at Satou who carries her injured body and at same time jumps--resembling flight--from building to building with both haste and caution so not further injure her. She jokingly later refers to him as Mr. Nimble because of his athleticism. They further become acquainted when she spots him in a front of a bookstore and a spontaneous date is born from their time spent together. She's gives her farewell to Satou when he leaves the city for Labyrinth city and they promise to write letters to each other from then on.
Journey to Labyrinth City
After Satou leaves Seryuu city for Labyrinth city, and approximately half month has passed, Zena is chosen as a member of the labyrinth city Selbira training selected corps--a force created by Earl Seryuu as a means to gain necessary knowledge in care-taking and commercializing Seryuu city's new labyrinth by studying the veteran Labyrinth city. This is all due to the collective agreement of Zena and her close friends Lilio, Ruu and Iona, who all had their own personal reasons for the joining the corps but wanted to help Zena achieve her love by going to the labyrinth city. Incidentally, within the corps Zena is the leader of a magic squad consisting of her and her aforementioned three friends.
The march of the corps had been relatively smooth with only insect-type monsters and minor thieves attempting to obstruct their journey until they enter the Lesseu Earldom then meeting the territory's defeated army and discover that Lesseu city has been destroyed by a mid-class, level 40, demon that also brought along 1400 rampaging monsters.to the territory. Further hearing that the monsters are stronger than average soldiers and the demon alone annihilated Lesseu city's army, Zena becomes anxious on whether her low-leveled corps (with three magic soldiers including her) can defeat the higher-leveled demon and monsters let alone repulse them. Surprised by the young lord, Earl Lesseu, who wills the cooperation of the labyrinth selected corps under the pretext of [Blue Covenant]; the oldest covenant that has been passed over among the nobles since the founding of Shiga kingdom. A covenant that indiscriminately decrees all forms of military in Shiga kingdom has to cooperate together in case of demon attacks. The labyrinth selected corps--thus Zena's squad--become part of an impromptu army at the second city of Earl Lesseu's territory. The whole force consisted of 800 regular soldiers, and 2000 militia. Even though twice the monster's number, the militia are padded forces. But Zena hypothesizes that if the demon attacks directly and they use the city's wall insisting on a siege war there are more chances of winning. But Zena despairs thinking she won't be able to keep her promise of sending letters to Satou when the young Earl Lesseu decides to fight the monsters and the demon on an open field despite the captains' pleas.
During the battle on the field, a black dust covered Zena and her squad are recovering from a daze caused by an advanced level tactical magic fired by the demon. Zena realizes that they are pinned by the approaching monsters waiting to take advantage and the demon in sky waiting to fire its magic without mercy. At that time, the sky is divided and Saga Empire's hero, Hayato Masaki, on his silver ship, Dimensional Traveler Jules Verne appears. With one of swing of his holy sword, Arondight, the mid-class demon is destroyed and the many monsters are destroyed by the ship's beam. Zena is awed by the overwhelming power of the hero, considering his intrusion in the battle to be a miracle. She then resolves herself that she wants to become stronger so that next time she will stand the one who creates such miracles.
After the battle with the exit of the hero, Zena and her squad, are searching for survivors. During so, Earl Lesseu, personally seeks out Zena, on the pretense of complimenting her good works during the battle. Aware that she's of the Chevalier Marientail house, he offers her the position of his retainer with honorary noble peerage with the promise of making it permanent depending on her work. Zena refuses the invitation because her family has served Earl Seryuu for generations and she has no intention working for another house. Not expecting such an answer the earl becomes slightly angered but reigns himself in, to the extent, he's able to promise a vacated seat as retainer for her if she changes her mind. Norina, a similar magic soldier to Zena in the labyrinth selected corps, informs her of the subtext of Earl Lesseu offering her a position; Norina was also offered such a position but not by the earl but by one of his retainers, which means there's was also a possibility of the earl attempting to court Zena as a future mistress and seeking her as a magic soldier for his own troops might have also been a pretext.
After ten days elapsing after the fight with the demon and heavy losses, a limbless Baron Derio, the captain of the Labyrinth Selection Regimen had returned early to Seryuu territory to brief the earl about the situation. Vice-captain Rilo who had also lost a limb informs the corps--via a carrier pigeon with a message from Earl Seryuu--that they are to continue onward towards Labyrinth city but those who have lost their will or have lost limbs are to return to Seryuu city. This includes Rilo who makes Knight Henz the new captain of the corps of a now 18 people (which was once 24 including 300-plus people under their protection) with two magic squads (including Zena's), Knight Henz attendants, civil officers and two squad-less soldiers going to Labyrinth City, Selbira.
Zena and the remaining corps entered Zettsu Earldom after defeating remnant monsters collected by the mid-class demon that had built nests on their way and at the borders of Lesseu and Zettsu. Zena haggard by the constant battles after the long journey from the north to the south of Zettsu Earldom, finally reach its southernmost city. Which feels her with hope because once they leave this city they will be entering the territory directly under the royal family and then its Labyrinth city where Satou awaits. Plans to move onward from the border city, Fau, are halted as Zena and the corps later find out that a lower-class dragon has nested in the mountain range on the territory's border preventing all caravans and journeymen from going to the royal capital which also includes the on-the-way Labyrinth city. A month passes without any progress or countermeasures against the dragon and they stay stuck in Fau city; their only choice would be to detour the mountain-pass the dragon occupies by going back to Lesseu Earldom, then go through the mountain range in the south route passing through Muno Earldom (of Shiga kingdom) or circumvent through several small kingdoms by passing through Eluett March (of Shiga kingdom). These options are not profitable as it would have extended their journey by several months or cast needless suspicion on them, if they as foreign soldiers, maneuvered in other countries.
Zena is informed by Lilio and Ruu who went to investigate for a shortcut, ten days ago, that though the shortcut is passable for the soldiers it would be extremely laborious for their accompanying civil officials and maids. They also inform her that the lesser dragon is 'probably a sub-species dragon-monster like wyvern or hydra because of its ominous and eccentric characteristics of spewing out mist that can melt rocks, its fondness for oranges and that it's actually larger than a lesser dragon. Zena, Lilio, Ruu then reunite with a young black-haired one-armed man, they were acquainted with in Seryuu city, who Zena had mistaken for Satou. The young man via Lilio tells Zena of a new shortcut that's even unknown to Fau city; where there's a road that goes pass the valley where the dragon resides but carriages can't pass through there, but there is a gentle slope for walking better than the the other shortcut.
After reporting to the captain, Henz, Zena's squad is instructed to scout out the shortcut with the possibility of meeting the dragon. With no hope of the Royal Army coming anytime soon to repulse the dragon and the exceeding prices of Fau city that made it had to secure provisions, Zena reluctantly resolves herself to carry out the scouting mission. In order to ascertain further information, Zena's squad again meet up with the one-armed man who Zena frankly calls 'Lilio's boyfriend' because of the other girl's romantic interest in the man. He informs them that the valley also has harpy nests and there are surrounding rocky areas that spring out slimes. During this conversation it is revealed that the man is named 'Jon' (or rather how Zena hears the pronunciation) by his female acquaintance, Mito, who calls out to him. Zena's squad then heads to the aforementioned Withered Valley, due to spraying steam from the ground, the trees there have withered. With the poor visibility because of the steam they move through the valley, and are taken by surprise by an attack from a harpy. But with practiced commands given by Zena, her squad take anti-air formations whilst she cast a sound protection spell against the sleep-inducing harpy leaving it to Lilio's crossbow to winged it and Iona to mercilessly smash its head with her great sword. Zena affirms the suspicious movements of the harpy when she realizes it was being chased by a lesser dragon who threateningly appears before them.
Zena's squad and the dragon have a stare down, Zena in distress forgets to breathe from the pressure in a solidified posture, then almost falling down from relief when the dragon loses interests in them to focus on the corpse of the harpy. Then the dragon is then distracted by a new intruder, the fourth seat of the Shiga Eight Swords, Trell the [Gale], who came to challenge the dragon on his wyvern. Zena worries for the Shiga Eight Sword, who she thinks is unable the beat the dragon who is equivalent to the greater demon that previously attack Seryuu city. When Zena's squad have lost control of the situation 'Jon' and Mito arrive on the scene as 'Jon' urges Zena's squad to move away from their current position in preparation for the incoming battle. Whilst watching the battle between the dragon and the Shiga Eight Sword, with the dragon overpowering the holy knight, Zena notes it's like 'like a cat playing with a mouse.' Overhearing the conversation between Mito and 'Jon', Zena is informed that the actual sub-dragon that was rumored to be in the mountain-pass was driven away by the lesser dragon and with that conclusion Zena's attention is robbed when both Trell and his wyvern are knocked down towards the ground. The wyvern gains various injuries that prevents it from being able to fly, and Trell whilst shedding blood prepares his last stand against the dragon asking his observers to hand down his deed. He accumulates his remaining magic power to activate the technique [Magic Edge Rupturing Strike] charging toward the dragon. Failing to make a greater on the dragon's defensive membrane of light that acts like an armour Trell is flicked away by the dragon rolling on the ground before losing consciousness.
Mito steps on the scene, first ascertaining whether Zena can use advanced level magic to heal the critical damages that Trell suffers not being dejected when Zena replies she can do so up to the intermediate rank. Mito speaks to he dragon, telling it that the fight is over, and the old man (Trell) can not fight anymore but the dragon disregards her comment and is still eager to fight and thus Mito decides to entertain it. Mito produces transparent blades and boards around her that look like something created with force art magic. They are like shields that protect her, like spears that eliminate foreign enemies, and like living creatures that follow her every movement. Zena notes all this whilst watching in awe thinking that it's like the offense and defense advanced magic of the Ancient King Yamato, paying special attention to the fact Mito did this without chanting. Zena continues to watch as Mito fires invisible rain of cannonballs hitting the surface of the dragon which gets repelled away. She exasperated by the situation where the dragon begins run away when the Shiga Eight Sword, Trell, was unable to be a formidable enemy for the dragon. Mito disappears into the Withered Valley's haze, Zena judges from the screams of the dragon and the joy and laughter from Mito, the latter is winning.
Finishing up the emergency treatment of Trell, Zena's squad try to uncover the mystery of Mito by asking 'Jon' who can only say he doesn't know more than the fact he found her sleeping beyond a hidden door in the depth of a ruin in Zettsu Earldom. Mito returns having tamed the dragon bidding goodbye to both 'Jon' and Zena's squad as she details she going to return the dragon to an acquaintance in Fujisan mountains. Zena can only watch her disappear into the sky on the top of the dragon, with Zena reiterating Mito's resemblance to Ancient King Yamato and the Dragon Knight that appear in the story of Shiga's kingdom founding. Zena's squad also part with 'Jon' and the Withered Valley deciding to return to Fau with Trell. Furthermore, plans to use the valley as shortcut were postponed when Zena via rumours discovers Nanashi had defeated the sub-dragon at the mountain-pass, whilst thinking the identity of the hero might be Mito. Thus the dragon disturbance ended, and Seryuu city's labyrinth corps were able to resume their journey towards the Labyrinth city after acquiring provisions from a kind merchant. After many mysterious cases through her arduous journey, Zena beams as she finally arrives at the gates of labyrinth city, Selbira, especially looking forward to her reunion with Satou.
- [One-Handed Sword]
Physical Combat Skills
- [Wind Magic] (Advanced)
- [Lightning Magic] (Basic)
- [Ice Magic] (Basic)
- [Healing Magic] (Wind-element)
- [Chant Shortening]
- [Magic Power Operation] (15-6)
- [Magic Edge] (16-11)
Wind Magic - Spells
- [Air Cushion]
- [Air Hammer]
- [Divine Sonic]
- [Fallen Hammer]
- [Heavy Air Wall]
- [Sound Protection]
- [Wind Protection]
- [Wind Walk]
- [Wind Stiletto]
Healing Magic - Spells
- [Healing Breeze]
Holy Magic Verses:
- <<DANCE>> (used with Wind Stiletto)
- <<CLAD>> (used with Wind Stiletto)
- <<APPEASE>> (used with Wind Stiletto)
- Yellow stole
- Pink stole
- Standard Seiryuu army uniform/armor
- Rifle-type magic gun [14-27]
- Silver armor (as Silver Knight Air)
- Short wand (as part of her Seiryuu army armor)
- Long evergreen oak wand (given by Kuro) [11-8]
- Wind wand
- Magic short sword (given by Kuro) [11-8]
- Stylish sword-belt (given by Kuro) [11-8]
- Holy sword (split into stilettos x7)
- Holy dagger [15-22]
- Dragon Fang dagger [14 Intermission 1]
- Zena (initially at least) pronounces Satou's name as "Sa-too" in the light novel and Japanese dub of the anime, with Satou commenting that his name may be difficult for people of that world to pronounce...but in the English dub, Zena pronounces Satou's name properly as "Sa-toh" normally as it should be.
- Zena's friends tease her that she's a fallen noble and vigorously encourage her to marry-up.
- Zena dreams of being able to fly; which includes her secondary goal of having a sky-date with Satou when she's able to.
- Zena, like Karina, looks up to heroes.
- It took three years of training and practice for Zena to be able to use wind magic.
- Zena is often troubled that she often can't give out commands when she starts to chant magic especially when she became captain of her squad.
- Zena thinks Mito is nimbler than Satou.
- Hayato remembering Zena after defeating the horse-head demon in Lesseu territory of Shiga Kingdom said he admired her "middle-schooler-level flat chest" and says he would have proposed to her if they met five years earlier.
- "I-I-I'm Zena, a magic soldier and a vassal of Count Seiryuu. I've served in his army for two years. I'm seventeen years old, unmarried, and s-single!" 
- "I want to become stronger. At least, in equal footing with the demon. For the shares of our fallen comrades too, we will become stronger. Next time, we will stand beside the one who creates the miracle!"