The Sterling family was an aristocratic lineage that ran a vast underground empire, yet the master and mistress had long been childless. After severing ties with a partner, Mrs. Sterling unexpectedly gave birth to twins. However, when the children turned four, they suddenly vanished.

Desperate to find their children, the couple became increasingly devout in their penance. The sister was quickly rescued from their former partner, but it took three more years to locate the brother.
On the day he returned, he sang the nursery rhyme when he and his sister parted, a rhyme about a game they used to play when they were young - Knight and Princess. With the melody and the details he recounted, the sister recognized him. The twins still seemed innocent, but something felt off to the sister who used to spend all her time with her brother. Until one day, she discovered that this “returned” brother was always lying.
He led servants to the rooftop and had the butler remove the ladder. He spread malice among the children, inciting hatred; he unearthed documents revealing their father’s ongoing illicit dealings, sparking fierce arguments between their parents that ultimately drove their mother to attempt suicide. The sister was the only one aware of these events, while the brother insisted that he loved her most and forbade her from telling anyone. “Only in a world this cruel will they cherish symbols of ‘hope’ like us."

The brother watched the chaos his lies caused from the shadows, like a king plotting a war, holding the pieces on his chessboard. Yet he often seemed lost in thought, troubled by some unspoken dilemma. As the sister approached marriageable age, burdened with all the secrets, she began to yearn for an escape from this mysterious brother.
However, on a sunny afternoon, he pushed her down the stairs. “As long as you can never leave, I will always be the ‘Knight,’ and you will never go to the outside world.”

It was only then that others began to realize his malevolence. They had all assumed he was merely a boy who loved reading, knight dramas, sword fighting and war books. Eventually, their parents discovered that in every family photo from before the twins turned four, the brother's face had been scratched out and replaced with "Richard’s" face.

Finally, when the sister was on her way to the red church for the wedding, Richard was confined to the dungeon. After the ceremony, she vanished without a trace, and the Sterling couple fell into an eternal slumber in the tower of their estate.
Now the sole heir, Richard Sterling still wears a polite smile, singing the songs of the “Knight” as he sets off on a journey to find his sister.