Takemi has dark blue hair in a messy bob-cut with blunt bangs and brown eyes. She has red nail polish on both her fingers and toes. She is fairly short. Her outfit consists of a typical white lab-coat that is worn over a short dark green dress. She accessorizes with a red grommet belt, a black studded necklace choker which connects to multiple necklaces, and strappy black platform high heels. She is noted by Morgana to have an "interesting fashion sense." Takemi is a somewhat eccentric young woman. She dresses like a punk and has a morbid sense of humor, reacting with glee when she gets Ren to try out a new medicine, watching him squirm. Due to her bad reputation, she can easily tell when one of her patients has an ulterior motive, as those kind of patients are all she gets. Her reputation as "the Plague" has made her highly cynical and insecure, claiming that she's only good for making experimental drugs, even after being praised for curing a young girl. Despite her dark sense of humor, Takemi is nevertheless a very kind and caring person, as one would expect from a doctor; although she gets annoyed at Ren for his attempted deception, she decides to make a deal with him afterwards, saying she'll give him medicines to recover his health. After he agrees to become her assistant, she frequently checks on him to out of concern for his health. However, she never calls him by his name, instead referring to him as "[her] little guinea pig."

Sojiro is a middle-aged man. He has slicked-back dark hair with a receding hairline, gray eyes, a chinstrap beard with a goatee that flares out and wears glasses. His usual outfit consists of a pale pink dress shirt with the sleeves rolled up, pale khakis held up with a white leather belt and white loafers. While working at Leblanc, he wears a black apron with a white pinstripe design on it and has his pants legs folded up to mid calf. During his off-time, he wears a white two-button blazer and a white trilby with a red-white-and-blue striped hat band. Sojiro is cold and strict to Ren upon first meeting him, begrudgingly taking him in as a favor to a friend. Like many characters in the beginning of the story, he is cautious of him due to his probation, even stating that he will do very little if Ren gets himself into trouble and threatens to kick him out if he violates his probation and does not appear to be willing to hear Ren's side of the story in good faith. He is a rather cynical person, warning Rem that he should be careful who his friends are and chastising him for getting involved in the affairs of others, even if he was trying to do the right thing. However, Sojiro seems to have a soft spot for cats, as he instantly changed his mind about throwing Morgana out of the house, after hearing him meow, claiming that he was "just too damn cute." He also made him something to eat right away, despite claiming that feeding him was Ren's responsibility. However, as Ren continues to live with him, Sojiro slowly builds trust in him, allowing him to go outside at night, first around the area then anywhere around Tokyo and even beginning to teach him to make Leblanc's signature coffee and curry. He also begins to joke around with Ren more, seeing that he is not the delinquent that his probation makes him seem like. Eventually, he opens up to him about his past with Wakaba Isshiki and her daughter, Futaba, up to and including why he took in the latter after the former's death. Sojiro is a very smooth talker and often charms women with choice words, stating that he was "quite the ladies man" in his youth. He provides the Ren advice for White Day, outlining a plan that he says is sure to impress his date, even allowing Ren to take advantage of the connections he has in the restaurant industry. Despite this, Sojiro has never been married and has only truly loved one person: Wakaba. Wakaba's "suicide" became one of his biggest regrets in his life, due to the fact that he took her warning that she may die soon as a joke. It is also part of the reason why he adopted her daughter, Futaba. Despite the life she lives as a shut-in, he allows her to do so knowing that her mother's death haunts her and to atone for doing nothing even after Wakaba foresaw her impending death. At times, he wonders if he really is the best person to raise her. After Ren helps Futaba to leave the Sakura residence and learning of both of their involvement in the Phantom Thieves, he begins to stand up for the protagonist and becomes supportive of their efforts due to their goal of taking down Masayoshi Shido, a man responsible for Wakaba's death. Once he finds out that Ren and Futaba (along with all their other friends) are part of the Phantom Thieves, he accepts it and promises to keep their secret, despite them being some of the most wanted people in Japan at that point. This is largely due to the fact that he always suspected that there was something more behind Wakaba's death, but kept his nose down because he did not have any real evidence.