She is a human who became half-Mystic, a vampire-like race, after nearly dying after being struck by a carriage and saved by being given blood from a Mystic named Orlouge.

She was intended to be a character who was able to thrive without men and whom women would fall for, though some of these aspects were not able to get past the planning stages, so Shoda instead made it a coming-of-age story.

Asellus was created for the video game SaGa Frontier, and is a woman who is originally a human who becomes half-Mystic, a vampire-like race, after being struck by a carriage and being given blood from another Mystic named Orlouge.

[3][4] Certain content was originally planned to be included in SaGa Frontier that expanded Asellus' story further, but it had to be cut due to development constraints.

Shoda wrote her to desire a familial relationship due to losing her parents at a young age, but rejected such a thing with Orlouge, as it was not the kind she wanted.

[6] Outside of video games, the character has appeared on multiple bits of merchandise to promote SaGa Frontier, including a long coat, wristwatch, bag, and wallet.

[9] Dengeki Online writer Go identified her as their favorite character in SaGa Frontier, having beaten the game with her multiple times, though lamented that unlike other protagonists she could not be recruited in most other routes for the title.

[12] Gamer writer Crazy Kawachi appreciated that her story could be seen as an introduction to the yuri genre, though felt even those that didn't recognize it as such still enjoyed those aspects of her character.

Seeley discussed how Asellus' rejection of her half-Mystic status mirrored that of a "young queer woman coming to terms with her sexuality," and how her later accepting she can't change who she is is a "meaningful message" for anyone.