Yuri is portrayed throughout the majority of the game as being shy, generous, polite, apologetic, very intelligent, mature, eloquent, and passionate about topics she is interested in, although she is also very insecure, awkward, and has a tendency to act slightly condescending and patronizing to mask her self-doubt. Her façade of passivity and level-headed nature occasionally breaks, however, as Yuri does argue passionately and aggressively with Natsuki over their differing opinions on writing styles and types of literature. Yuri has a deep desire to be liked by others and is afraid to speak her mind on certain matters as she believes it will make her seem unlikable. Due to her social ineptitude, she can be innocently insensitive, but once she realizes what she said could be considered rude, she almost immediately apologizes, repeatedly saying she did not mean it. As stated by the protagonist, Yuri likes to think before she says something.

Yuri prefers to blend in with the scenery than to attract unwanted attention. The attribution is also because of being shy to discussions beyond her category of interest, her interests being literature, horror, and general surrealism, which she examines and articulates expertly and encourages others to follow as well. During Act 1, Natsuki and Yuri get into a debate about their different writing styles. Choosing to side with Natsuki will cause Yuri to shy away from the player, and if the protagonist attempts to read their poem to Yuri, she will not respond, which will cause the protagonist to decide it is best to leave her alone. If the player calls for Sayori to diffuse the situation, Sayori will compliment both Yuri and Natsuki on their writing, appearance and capabilities. This strategy will satisfy both girls, but also leave them embarrassed.

Yuri's love of surrealism seems to be foreshadowing further events of the game, with Yuri's surrealistic eyes and the game's sudden shift to horror after Sayori's suicide. Yuri prefers poetry that uses metaphorical symbolism and enjoys collecting unusual ornate knives, which are implied to be used for self-harm. The detailed summaries of the Portrait of Markov novel in the first and second act, when also taking the scattered dialogue references into account, all end up tracing back to her unstable nature and unhinged personality.

Yuri takes great pride in her poetry and perceives her poetry as being superior to that of the other club members, especially Natsuki. According to Dan Salvato, this is a coping mechanism for her deep insecurity and self-doubt, convincing herself that she is the sophisticated, mature one and that her critics or rivals are immature and childish. This can make her seem arrogant and patronizing to those unfamiliar to her. This desire to seem intellectual is reflected in her poetic style. Her poems are so full of metaphors and advanced language that the meaning is often obscured, or even lost. In Monika's Talk, while talking about Yuri's habit of drinking tea while reading, Monika wonders whether Yuri is as passionate about certain topics as she makes out, or whether she is "just concerned about appearing sophisticated to everyone else."

Yuri has trouble making and keeping friends, as she tends to come on too strongly, due to her intense desire to be liked. She used to be judged for her appearance and mannerisms, providing another possible explanation as to why she secludes herself to her introverted lifestyle. She is, however, a generous and giving person, exemplified by her giving a copy of Portrait of Markov to the protagonist and for bringing tea to the Literature Club to help soothe the mind and help stay focused during reading.

During Act 2, Monika amplifies Yuri's negative personality traits, causing her crush on the protagonist to become an unhealthy obsession, at one point Yuri admits that she touches herself with the pen she took from him, and her already-existing hobby involving knife collecting becomes a love of self-harm, to the point where Monika suggests that Yuri cuts herself due to a fetish. This also causes her to become invasive and condescending to the other club members, asking Natsuki "Why don't you look for coins under the vending machine?", which causes Natsuki to cry and run away. In one occasion, Yuri shows a poem to the protagonist with blood and waste stains on it, telling him that she has 'put her scent on it'. Yuri will then realize what she has truly done and leave the club, stating that she is going to vomit.

If all three poems are written for Yuri in Act 2, the scene where Yuri is discovered to be cutting herself will happen once more, but then will show Yuri with blank eyes and a glitching sprite. Afterwards, she will be mildly unsettled, mentioning that she had some serious deja-vu. She then will talk about how she’s always despised how she got a little too excited about certain topics that caused her to isolate herself from other people. She then asks the player about Monika, and how she's changing from a sweet girl to more manipulative. But then, she will state that they are finally alone, away from "Monika's slimy tongue" and Natsuki who is a "pathetic child". Then, she will try to convince the main character to stay with her, and will seem to be overtly excited, with randomly glitching pupils. Monika's sprite will also slowly fade into view, covering Yuri while her dialogue continues.

Yuri recognizes that something is wrong with her and that her comments and behavior are inappropriate, enough so to feel something bad will happen despite her happiness. She is ultimately unable to control her obsessive outbursts, no matter how hard she tries. It reaches a point where, after she confesses her love to the protagonist, she stabs herself to death, regardless of whether the player accepts or rejects her love. Yuri's body is left decomposing for three days, and is then discovered by Natsuki, who immediately vomits and runs away. When she is discovered by Monika, both Yuri and Natsuki's files are deleted, leading to Act 3.