anko2897: The Un-yu
In a family of strays living in a park, a defective Reimu is born. The firstborn Marisa pities her sister and pleads with her mother not to kill her, so the mother casts the baby out of the house instead. Although she is undersized, grotesquely misshapen, and unable to speak properly, she is highly intelligent. The Reimu survives alone on the streets, training her tiny body to achieve super-yukkuri strength, speed, and agility. Wielding a fruit knife, she kills other stray yukkuris to maintain a reputation as someone not be messed with.
She plans revenge on the clan who rejected her, but on the day she goes to carry it out, a factory extermination squad is already there doing her work for her. As she watches, one Marisa escapes and recognizes Reimu. It is her sister, the only yukkuri who was ever kind to her. Reimu lets her live--and even saves her from a bodied Flan.
Marisa follows Reimu and becomes part of her life, and with their love for each other, they decide to have children, although Reimu has qualms. Marisa becomes pregnant.
Meanwhile, the factory is investigating the strange increase in dead yukkuris found in a particular neighborhood and the unexplained death of one of the extermination Flans. A grizzled yukkuri hunter known as Oni Toshiaki suspects he may have found his ultimate opponent.
ENDING: Toshiaki tracks down Reimu. Finding her emergency exit blocked, Reimu launches an attack with her knife, but Toshiaki stops her blade between his teeth and grabs her. Having caught his target, Toshiaki crushes and kills the pregnant Marisa at his feet. As she's driven to the factory, Reimu wonders how she could've changed her unhappy fate.