Sui

A nine-year-old mute born in Luoyang. Her sister was killed by the swine demon that also dwells in Luoyang. To avenge her sister’s death, she intentionally let her self-become abducted to get close to the demon and assassinate him. Some, or all of the above statement is false, part of Sui’s untrustworthy nature.

Spoiler

In fact, she is 13 - 14 years old and never had a sister. Her initial purpose was to exact revenge on the protagonist, since he killed her father, which led to all their family starving to death.