Hong Lu is of average height and build, with a pale complexion and raven black hair. Her hair is very long, and tied into a high ponytail with a cyan hair tie, which she wears in most of her Identities. Notably, she has heterochromia: her right eye is black, and her left eye is a bright cyan.

Her typical outfit consists of an LCB uniform consisting of black pants, a white long-sleeved dress shirt with a red tie, under a black, low-cut vest tucked into a belt. Additionally, Hong Lu wears a long black coat that reaches just above her ankles. This coat has her Sinner number on his left, and a metal pin inscribed with her name on the right.

Hong Lu carries a long guandao called "太虛幻境" (pinyin: tài xū huàn jìng; lit. 'Illusory Land of Great Void'), which she wields with her right hand.

When seen during her childhood, Hong Lu had a similar hairstyle, and she typically donned a white hanfu with light blue and gold decorations, beneath a white beizi. When seen during his adulthood in Daguanyuan, Hong Lu sported a similar look, consisting of a cream-colored hanfu with teal decorations, and a matching beizi

Hong Lu is an exceptionally curious person with a rather ditzy demeanor and friendly attitude. She exhibits a potent, almost childlike indiscriminate curiosity and wonder, to the point of baffling the people around her. While this implies having lived a sheltered lifestyle up until her employment with Limbus Company, a closer inspection into Hong Lu's life will reveal that she grew up in a difficult family full of danger, betrayal, and lofty expectations. Hong Lu speaks casually of attempted murder and abuse against her in a similar way to how she approaches the hardships of the City, almost as if it has nothing to do with her. She has a tendency to give off the impression that he doesn't have particularly strong feelings about anything, regardless of the severity of the topic. While sometimes jarring, this trait primarily serves to make Hong Lu come off as amusingly easygoing and absentminded.

Hong Lu also appears to lack inherent social tact, leading to excessively oblivious statements and questions when something inevitably catches her eye. While this does earn her some disapproval, she does not grow angry or depressed when others give her a difficult time. Hong Lu will either playfully disregard words of scorn, or is altogether too oblivious to be hurt by them, at least outwardly. Although some matters may lead to her growing more obedient or solemn, Hong Lu will consistently let anything and everything slide right off of her back without complaint or meaningful retort. This lends to the impression that Hong Lu is denying herself the chance to experience his true feelings, which is later shown to be the case. Nonetheless, she maintains an exceptionally cheerful, carefree attitude throughout Limbus Company's first year together. She is additionally very amiable and shown to be open to striking up neighborly conversation with everyone he comes across.

Despite this, Hong Lu is neither loud nor particularly talkative. Rather, she comes off of as reservedly observant. Canto IV: The Unchanging is the first story chapter to give insight into Hong Lu's unique perceptiveness and emotional intelligence. She takes the role of Young-ji in the League of Nine play, who Yi Sang describes as the most gentle and heartfelt of the League in their heyday, and contributes tender observations pertaining to Yi Sang's mental state and growth throughout his Dungeon. Here, Hong Lu demonstrates striking maturity and self-control in contrast to his usual attitude.

Canto VI: The Heartbreaking through Intervallo V: Nocturnal Sweeping build on this more empathetic, delicate side of her character. While her ditzy self remains, Hong Lu also demonstrates that she is a highly gentle, insightful, and understanding individual at heart. In tandem with her emotional maturity, however, grow Hong Lu's own signs of distress, and she reveals a passively suicidal mindset alongside a perceived lack of free will. These traits, revealed to have formed with the traumatizing fall of the Kong family, are pushed to an extreme when her old connections comment on his learned helplessness as her wider family takes advantage of his unwillingness to be true to herself. Yet with Jia Qiu's guidance, Hong Lu's adventure culminates in her denying the family elders who had long stripped her of his autonomy, as the "gem of the Jia family" relishes in the emotions she had always forced herself to swallow.

Following the confrontation with her grandmother, Hong Lu is more emotionally reflective than ever. While her years of abuse cannot be undone, she shows a quiet determination to avoid holding her tongue and preach the kindness she believes in. Having made new bonds, mended old ones, and accepted the loss of others, Hong Lu grounds herself to the present with its variety of opportunities for happiness, wrath, sorrow, and joy.

In this world, Hong Lu is a Fixer from the Section 3 of Cinq Association's Eastern branch. She wears a black changshan decorated with the Cinq symbol, white pants, and a black jacket over her shoulders, and a black hat, In combat, she uses martial arts enhanced by a pyrojade bracelet on her right hand. She can be seen in her Cinq Association East Identity.