Stheno, Class Name Assassin, is the Assassin-class Servant summoned by Ritsuka Fujimaru in the Grand Orders of Fate/Grand Order. Stheno and Euryale are identical sisters called the "snow-white Gothic Lolita duo." According to her, the weight is "the same as I (Euryale)". Stheno was pictured as the "ideal woman", displaying an elegant demeanor, an overflowing grace, and the wisdom in her actions and words. It is said that men will lose their senses over the rapturous feeling and swear eternal loyalty to her should just their names pass from her lips. Unlike their younger sister who is an expert in fighting and disliked humans, she and Euryale perfect themselves as idols who liked humans, welcoming the men visiting the island, comforting them, and sending them on their adventure. Though her image on the surface seems to paint that as the very meaning of her existence, that is only to those observing them from afar. She is a devil who loves everything pretty and cute, freely and unconditionally. While she loves humans, it is not as "living beings", but rather in the way of toying with those she likes, embarrassing and driving them to ruin while watching them struggle. In reality, they truly hate men, while their sister is the one who bares them no ill will. They, loved by men, should be destined to be violated by them day after day. Though she despised her fate, Stheno had given up until Medusa became the one to protect them. Along with her sister, they like to suck her blood, noting that it is extremely sweet. Due to remaining the same as her sister eternally, they have a closer link than even telepathy, like two parts of the same body who share the same senses, feel everything the other does, and share the basics of their personalities. They will often speak as if they are one person, using singular pronouns to describe each other. No matter what kind of gentleman one may be, he will praise and flatter her. Although endowed with elegance and refinement, if one were to get to the core of her character, it is also possible to say that she is an extremely lazy person. Exceedingly coldhearted towards a trivial party. To the point of making the watchdog of the underworld (Tartarus) shudder. She has no wish to offer the Holy Grail. If pressed to say, it would be "for us three sisters to live together forever", but she is already aware that this is a wish that can never come true. At the time of her unlikely manifestation, there is only one thing in her mind. Whatever it is fun or not.