Born to an Adeptus and a human, Kui Xin was born and raised in Liyue Harbor. As a young man, he was taken in by the Qixing and now works as executioner to the standing Tianquan, a position he's very proud of. After so many years, not many people recognize him in town anymore, but the only company he needs is the moonlight.

Kui is regarded as a fun and free-spirited individual. And also rather prideful. There's nothing that Kui Xin enjoys more than showing off, often boasting about his adeptal power. Do not be fooled by his overzealous persona though; he is most certainly as dangerous as he claims- when it comes to humans at least. Living with mortals has caused him to be reckless and overestimate himself, sheltered from the world outside of Liyue, and even the Harbor itself. Were true danger to ever rear its head, would he be able to stand up against it?

Kui Xin's story begins with "The Perfected Lord who Dances on the Moon and Sings to the Stars", the Illuminated Beast who saved a lowly mortal man and fell in love with him on his travels. "You're nice to have around," said the man, extending his hand as he explained why he wished to form a contract with the Adeptus. The details of such contract were known only to the two that made it, but were Morax to judge it himself, he may compare it to that of marriage. Moon Dancer and the mortal spent many a night together, until the creation of their shared love came. No one can say for sure why Moon Dancer returned to her palace in the sky following Kui Xin's birth, but as darkness fell over Liyue, the man knew that it was what she had wanted.

Taking up their son in his arms, he returned to Liyue Harbor, where he raised and loved the boy till his eyes grew weary and his body old. Though the man had tried to prepare Kui Xin for his demise, the pained wail that sounded from his heart into the unfaltering rain and cried out to the Harbor brought all those within it to tears. Following the passing of his father, Kui Xin was given to the Qixing, signed away as their servant by his father to guarantee he'd be taken care for as long as he lived. The first Tianquan he served under was a cruel woman who guided him on a path of darkness to eliminate her rivals. It was her that declared him as Executioner, and execute he would do- forcing his pain onto any who opposed him.

The coming bodies of the Qixing pulled him from the heavy fog of loss that followed him, though he would still feel nothing but the hate of his own immortality as friends of old passed while he remained unchanging. The current Qixing under Ningguang in particular has given him justice to persue instead of wrath, the sense of pride in his role now evident to the traveler and anyone else who can know of his work. Yet inside him persists the fear of being unwanted and unneeded- the sense that he is nothing more than an imposter in the lives of Liyue's residents and his existence as an adeptus was a mistake.