The one-shot was originally published in the May 2017 issue of Jump SQ on April 14, 2017. The one-shot was later reprinted in Shōnen Jump+ on June 14, 2021, in place of a normal SPY x FAMILY chapter, with extra content describing its connection to the manga series.
Gath has built a reputation for being the strongest warrior in the country due to his natural resistance to the lethal poison produced by magical beasts, earning himself the nickname "Iron-blood Gath." One day, while out on a subjugation mission targeting magical beasts, Gath meets a young Medusa who instantly becomes attached to him due to Gath's resistance to her petrifying attacks. Uncharacteristically of him, Gath decides to take her home to the capital...
The chapter opens up on Gath's childhood with his father, a scholar passionate about magical creatures and frequently brought home poisonous magical creatures, including a poisonous koala and a paralyzing chihuahua. Even when Gath was bitten by the poisonous magical creatures, his father would simply tell him that he would produce antibodies against them.
The scene cuts to a now grown-up Gath who slashes at a magical creature and commands his squad to exterminate the magical creatures. After the battle, a soldier from his squad urges Gath to get medical aid quickly due to the earlier magical creature being armed with a lethal poison but Gath dimisses him and mounts his horse. Jedd, his subordinate, informs the soldier that poison and paralysis don't work on Gath's body, and calls Gath creepy for getting his condition from growing up with magical creatures. Another soldier warns Jedd off, revealing that Gath's father passed away before the battle.
Gath cuts off the arm of a frog-like magical creature and chases after him on his horse. Gath ends up alone in the forest and rubs the wound on his face as he expresses annoyance at the creature for running away quickly. Looking at his blood-covered sword, he recalls his memories of trying to get his father's attention by catching a small goblin as a child and showing off the cruciform medallion he earned for subjugating magical creatures, but his father continued to ignore him. As he cleans his sword, he chastises himself for remembering now. His horse is alerted to something and Gath quickly turns, but realizes it's the frog-like magical creature from before, now turned to stone. His horse notices something again and squeals loudly before turning to stone itself, falling onto the ground.
Gath looks around warily as he realizes it's the doing of a magical creature with petrifying abilities. When he hears a sound, he sees a small girl with a head of snakes munching on the neck of his petrified horse. They stare at each other, Gath surprised that the culprit is a child. The child then hugs his leg with Gath wondering if she thinks he's from the same clan or interested that he's not getting petrified. The child breaks off the leg of his petrified horse and attempts to offer it to him as food, but he rejects it as he can't eat it. Gath contemplates whether to kill her for the safety of the village nearby, conflicted due to her being a child. When he moves his sword slightly, the child is startled and quickly runs off before he can make a decision.
Gath decides to follow her trail to find her nest and look for her parents. After struggling through plants that have turned to stone, he discovers a home made out of stone with just holes for windows and doors. Entering the home, he notes that no one is around and wonders if he's misjudged. He sees a journal with the title "My Baby" written in human language on the front. Flipping through the book, it's revealed to be a nursing diary as the mother details the birth of her daughter and her plot for revenge against the humans who scarred her face by mating with the most ugly man to give birth to the most hideous daughter. However, her daughter's hideousness is to the point that she begins turn everything around her to stone, including her mother, despite them coming from the same species. Fearful of her daughter's powers, she decides to run away in the night but regrets being unable to see her daugter's sleeping face.
Gath turns towards a loud sound, which turns out to be the child giving another petrified offering of a small boar with antlers while she peeks at him from the doorway. Gath attempts to ask her if she's always been alone there but the child only knows how to say "Mi". He takes pity on her and decides to leave, apologizing for bothering her, but the child clings tightly to Gath's leg with her snakes biting him as she wishes to go with him. Gath expresses annoyance that he would take her along if only she were more adorable but is hit by curiousity whether the strength of her petrifying abilities would decrease if her hideousness is reduced. He asks her if she wants to come to the capital.
At the capital, fireworks are being set off as the city celebrates the success of the Nigrette Company in subjugating the magical creatures. Gath rides out front with the rest of his company riding behind him. Despite the cheers, Gath looks disinterested. Jedd asks Gath who the child following behind him is, the child now wearing a full helmet to cover her snakes. Gath says she's a servant. At the Anti-Monster Intelligence Sect-2, Gath seeks out the colonel to ask him for permission to personally investigate something. As Gath is about thank the colonel for his help, he spots the child running around the garden without her helmet. He quickly attempts to distract the colonel from looking behind. Gath puts the helmet back on her and scolds her for running around. She offers him another petrified bird. When Gath is about the admonish her, he's reminded of his younger self and realizes this is how she tries to get her parent's attention. Deciding that it's inconvenient to not have a name, he names her Misha and introduces his name to her. Misha calls him "Ga", causing him to blush slightly. He tells her they're going home to give her a shower.
Gath tries to clean Misha's head of snakes as she shivers, clearly causing the snakes great distress. Eventually, one of the snakes snap and bites onto his pinky finger, ripping it off. He later asks a scholar for a way to calm down snakes, writing it down on a notepad. Gath looks through his belongings for a makeup kit, attempting to give her a makeover as an experiment. Due to his lack of knowledge, the makeup doesn't work out, as he sends her outside but she proceeds to accidentally petrify two butterflies and they bury them.
At a brothel, Jedd attempts to brag to a woman about his accomplishments, but loses his temper when the prostitute asks him to introduce her to Gath instead. He spots Gath attempting to sneak in and calls him out. Jedd offers to let him pick a woman and talks about one of the prostitutes who has half her face scarred by poison, calling her hideous. Gath is yanked away by Regina, the prostitute mentioned, and she drags him away. In the room, Gath tries to console Regina for being called ugly by Jedd but she says she's not bothered by it. Gath asks her to make Misha cuter and Regina initally misunderstands that he means to make him cuter. When Gath reveals he bought a child of a magical creature to the capital, Regina is upset at his reckless behaviour and gets even more upset at him for throwing away his efforts when he suggests he should retire from the army. He tells her he worked hard so his father would look at him and now a medallion is nothing but a stone.
Regina asks him he wanted her to do. Misha is revealed to have been in the bag Gath was carrying along and he asks Regina help apply some makeup for Misha. Regina panics that she'll get petrified if she applies makeup to Misha, Gath reassures her that he read that she won't get petrified if she looks at her through the mirror and that he has a cure in case she gets petrified. Regina angrily questions why he decided to drag her into being an accomplice and Gath tells her it's because he knows she's dependable and won't sell him out, causing her to blush and she reluctantly agrees to help. Misha sits in front of the mirror as Regina nervously prepares to do her makeup. Gath reminds her not to look down. When Misha shows her eagerness to get her makeup done, Regina realizes that she's still just a girl and apologizes for calling her a monster, doing her makeup with more confidence. Regina's skillful hands quickly turn Misha more adorable and in her excitement over Misha's new appearance, she accidentally makes eye contact with Misha which causes her hands to begin to petrify and she has to drink the cure.
Seeing Regina cry in fear from being petrified, Misha is reminded of her mother pushing her away. Gath is optimistic after noticing that she only petrified Regina's extremities after her makeup, wondering whether to get her dentures. Regina reminds him to buy shoes first and becomes disgusted when she finds out Misha is actually wearing Gath's shorts, dragging them out to go shopping. As they prepare to go out, a pairs of shoes behind a wall show someone has been listening in on their conversation. Regina buys Misha a new pair of shoes, a new dress, and even dresses her snakes with bow ties. As they walk through a market, Misha sees a mother praising her son and feeding him a reward, noticeably losing her spirit. Gath sees a poster for a circus.
At the circus, Regina and Misha are greatly excited to visit a circus for the first time. Misha points at a clown to point out the similarity with the makeup Gath did for her. Behind them, someone purposely points out Gath's identity as the "Iron-blood Gath". Due to his popularity, they're quickly mobbed by his admirers and fans. Regina is annoyed by them fawning over him but realizes Misha has gone missing.
As the circus performance begins, an employee at the backstage area notices someone coming in. He warns that customers shouldn't come in but is turned to stone. Misha's kidnapper is revealed to be Jedd as Misha cries out. Gath and Regina are looking around the circus area for Misha, thinking that she's wandered off. He hears her cries, quickly rushing into the backstage area and sees the petrified employee, along with more petrified circus animals and staff. Regina is horrified at the sight and Gath reminds her to look down. Jedd shows himself to Gath, to Gath's shock. Jedd tells Gath he will keep it a secret due to Gath's importance but that he intends to use Misha to turn everyone to stone and the reap the rewards by being the hero. Gath angrily demands Jedd to let Misha go. Seeing Gath's persistence, Jedd decides to report Gath's crime and handle him by shooting him instead. Jedd attempts to shoot Gath but fails when his gun is turned to stone, as well as the ground.
Gath realizes Misha's crying face is so hideous that her powers are going out of control again. As Jedd attempts to take out a knife to deal with Misha, Gath rushes at Jedd and punches him down. Gath tries to console Misha but she slaps him away. Meanwhile, the main circus tent is turning to stone and cracking to pieces. Gath panics over what to do to resolve the situation. Regina tells Gath that she's at her limit as her hands begin to petrify. Gath instructs her to leave first. Gath hugs Misha, reassuring her that he won't leave or look away from her as the circus breaks to pieces around them.
Outside, the circus tent fully collapses. Regina cries out Gath's name and runs towards the ruins, crying that Gath could've embraced her before he died. Gath bursts out from the ruins of the circus, yelling at Regina not to say embarassing things in public. Regina asks about Misha and Gath reassures her that Misha is alright and even fell asleep in Gath's arms. Seeing the crowd gathering around the circus, they quickly make a run for it, as even the army is investigating the scene. As they are running away, Regina realizes that she didn't petrify despite looking at Misha and pokes Misha's cheek happily. Regina suggests the three of them live the rest of their lives somewhere quiet. Gath rejects her, saying there's someone who wants to look at Misha's sleeping face.
The colonel visits Gath's house, talking about the recent incident and the rumors of a Medusa appearing. Gath is nervous at being found out. Misha runs towards him with Regina chasing behind, causing Gath to spit his drink. Gath quickly tries to make up an excuse but the Colonel winks at him, revealing he knew about everything and agreeing to keep it secret. The colonel is here to deliver news about Misha's mother, having discovered that she would by the house every night of the new moon. The news affirmed Gath's suspicions as the house was well taken care of despite the last diary entry being a few years ago. The colonel had subordinates explain the situation to Misha's mother, thought she initally believed Misha had been kidnapped and she was under attack. He explains that Misha's mother is grateful to Gath for helping Misha's abilities and now awaits Misha's return. The colonel tells him that his father would be proud of him as his goal was to get closer to magical creatures.
Gath, Regina and Misha ride a carriage back to Misha's home. Misha wonders where they're going so Gath tells her they're bringing her back to her mother. Misha tears up from being able to see her mother again then asks about Gath and Regina. Gath explains that he and Regina won't be able to stay with her, bidding her farewell. Misha hugs Gath and tells him she loves him with Gath holding back his tears. Gath tells her she can come visit the capital anytime but to wear makeup just in case. They arrive at their location and Misha smiles at them before running towards her mother.
Gath Nigrette (がス・ニーゲレット, Gasu Nīgeretto?)
The Captain of the Nigrette Company, also known as the "Iron-blood Gath". He's especially popular with the townsfolk and ladies, much to the chagrin of Jedd, his subordinate. Due to his father's passion of bringing back poisonous magical creatures when he was a child, he's gained an immunity to all kinds of poisons.
Gath is a well-built man with short blond hair. He has a scar that runs down from his eyebrow to the side of his eye on the left side of his face. He grows a light stubble on his chin.
Misha (ミ"ーシャ, Mīsha?)
The daughter of a Medusa clan born from the union of a Medusa and an ugly human man, out of her mother's revenge against humans. The strength of a Medusa's petrification powers increases with their hideousness. She is abandoned by her mother when her petrification powers become too strong and is left alone for a period of time.
Misha is a small child with purple snakes growing from her head and round yellow eyes. Her teeth are jagged and her nose is slightly upturned. When Gath first meets her, her face is covered with dirt. Later, Regina helps to do her hair by braiding the upper snakes, tying it with a red ribbon, and curling the lower snakes.
Regina (レジーナ, Rejīna?)
A prostitute at the brothel who had the right half of her face scarred by poison, and is noted to be pretty good despite being said to be hideous. She is good friends with Gath and appears to be interested in him, as she blushes around him and suggests they settle down together.
Regina is a young woman with long black hair, her long bangs swept to the right to cover the right side of her face and her hair tied into a knotted ponytail.
- Gath's horse is named Triumph.
- The one-shot is inspired by Aishiteruze Baby with the character Yuzuyu influencing Tatsuya Endo to write a "small child character".
- Misha sneezes whenever her snakes are touched.
- Regina wears a hairband decorated with small roses and a rose necklace, similar to Yor.