Blood River

Also known as: Kui, Umbrella Ghost, Zhuo Yue'an , Zhou Ye An, Kui

Originally the young master of No-Sword City, he lost his family in a tragedy and was taken in by Blood River, becoming the Nameless of the Su family known as "Kui." He leads the Spider-Shadow assassin unit and lives by his own creed, the Three Refusals, refusing to slaughter whole families or take missions without cause. He protects the dying Patriarch while trying to steer Blood River out of the shadows, eventually becoming Head of the Su family. His central conflict is balancing loyalty to Blood River with his desire to free its members from being anyone's blade.

Also known as: Undertaker, Nameless of the Su Family

Su Mu Yu's sworn brother and closest friend, rising fast within the Su family with the codename Undertaker. He wants to reform Blood River from within, eventually taking control of the Su family and gathering a like-minded faction called Other Shore to push toward legitimacy. His methods grow increasingly ruthless as the series progresses, creating friction with Su Mu Yu even as their bond remains unbreakable. Their diverging visions for Blood River's future form one of the drama's central relationships.

Also known as: Miracle Physician, Miss Miracle Healer

A divine doctor and the daughter of Su Zhe, skilled in medicine and proficient with silver needles that can heal or harm. She becomes Su Mu Yu's love interest, offering him glimpses of humanity outside the world of assassination. She is presumed dead for years after a battle, secretly saved and kept hidden by Su Yun Xiu on the condition Su Mu Yu not be told, before reuniting with him after a long separation.

Also known as: Former Kui

An elder of the Su family and former holder of the "Kui" codename before Su Mu Yu. He is Bai He Huai's father and one of the former top experts of the Su family. He mentors and fights alongside Su Mu Yu during the power struggles that follow the Patriarch's poisoning, including transferring his own qi to save Su Mu Yu in a critical moment.

Also known as: Rabbit, Mao Rabbit

A member of the Mu family, one of Blood River's three founding clans, known for her skill with poisons and regarded as the most beautiful woman of Blood River. She becomes romantically entangled with Tang Lian Yue, though their relationship is complicated by duty and separation. Her storyline intertwines personal desire with the broader clan power struggle.

Also known as: Black Tortoise, Xuanwu Guardian

One of the Four Guardians of Tianqi City, representing the Black Tortoise, and a member of the Tang Clan (Tangmen). He is romantically tied to Mu Yu Mo, though his eventual rise to head of the Tang Clan (Tang Laotaiye) places new burdens on their relationship. He is drawn into the conflict against the Shadow Sect and its poison master, Tang Ling Huang.

Also known as: Poisonous Blossom, Poison Blossom

A member of the Mu family known as the "Poisonous Blossom," her body is saturated with poison from practicing the Toxic Sand Palm technique, letting her kill with a single touch. She is captured at one point and stripped of her poison against her will. She is romantically paired with Mu Qing Yang, and the two ultimately sacrifice themselves together holding off enemies to let others escape.

The former Patriarch of Blood River, who held authority for thirty years, ruling over the three clans of Su, Xie, and Mu. His poisoning at the start of the story sets off the central power struggle among the clans. He is noted for once sparing Su Mu Yu and Su Chang He from execution after they broke Blood River's founding law, recognizing something extraordinary in their defiance.

Head of the Mu family, one of the three founding clans of Blood River. Following the Patriarch's poisoning, he is one of the family heads vying for the top seat, dispatching assassins in the ensuing power struggle. He represents the Mu family's ambitions during the succession conflict.

Also known as: Diviner, Nameless of the Mu Family

The Nameless of the Mu family, fond of fortune-telling, who later becomes Head of the Mu family. He is paired with Mu Xue Wei, and the two share a close, playful bond with Su Chang He as well. He ultimately dies alongside Mu Xue Wei in episode 35, having planned to stay behind so others could escape a losing battle.

Also known as: Mu Yu & Chang He's Master

The martial arts master of both Su Mu Yu and Su Chang He. She plays a pivotal role later in the story by secretly saving Bai He Huai's life after she is presumed dead, on the condition that Su Mu Yu not be told — a decision that keeps the two separated for roughly twelve years.

Also known as: Prince Langya, Lord Langya

The younger brother of the Emperor of the Beili Kingdom. He becomes an ally to Su Mu Yu and Su Chang He, who seek his help to bring Blood River out of the shadows and into legitimacy. He is driven by a desire to pave the way for those he cares about, even at cost to himself, and his path with Blood River ultimately diverges from theirs by the finale.

Also known as: Night Crow

Known as the Ghost Physician, Ye Ya serves as an aide to First Prince Xiao Yong, working under the alias "Night Crow." She captures and strips Mu Xue Wei of her poison for use in experiments, and later controls Tang Ling Huang as a drugged puppet, deploying him as a weapon against Blood River's allies. She represents the darker, more clinical side of the First Prince's schemes to seize power.

The Left Shadow Guard Commander within the Shadow Sect, an organization tied to the Imperial court and led by Yi Bu. His role connects Blood River's conflicts to the wider political intrigue involving the Shadow Sect and the imperial family.

Also known as: Snow Moon Sword Deity, Xueyue Sword Deity, Second City Lord

A prominent and powerful swordswoman known as the Sword Deity of Xueyue City, serving as its Second City Lord. She is one of several Sword Deities who factor into the wider jianghu politics surrounding Blood River and the Beili Kingdom's sects.

Also known as: Crown Prince

The Crown Prince of the Beili Kingdom, son of Concubine Rong. As Blood River grows entangled in court politics, Su Chang He orders his assassination, an act that alienates Su Mu Yu and fractures their brotherhood, marking a turning point in the two leads' diverging paths.

Also known as: Scholarly Sword Deity

Known as the Scholarly Sword Deity and Dean of Shanqian Academy, he is one of the sword deities within the wider jianghu world surrounding Blood River. He helps rescue Li Han Yi alongside another ally after grief over Zhao Yu Zhen's death causes her to succumb to a dangerous demonic affliction. He also spends time with her guarding Prince Langya in Tianqi City.