It's implied that, like Monika, Yuri suffers . She has a hobby of cutting herself even when at school. If you choose her place in the first act, she will be wearing a sweater, implying that she may be hiding scars in her (non-existent) soul. She has been writing for a long time, making her one of the more experienced club members.
Yuri is obsessed with the Player character. When she spends time with the player character in the second act, she becomes angry with him. She also spills some blood on poems. She becomes quite "nice" towards her friends if she feels like they're trying to take the player character away from her. At one point, she accuses Monika of being jealous of the player character being with Yuri and politely suggests that she kill herself. After she forces Natsuki and Monika out of the room, she confesses her everlasting love to the player character and screams at him if he accepts her confession. No matter what the player chooses, Yuri will stab herself three times , then bleed out and die.