|Appearance||Period 39: At Emily-chan's Home|
Yukio has short light-colored hair worn in a bob with her bangs mostly parted to the left and a small split on the right corner. She has big and wide eyes. In the animated adaption, her hair is grey and she has teal eyes.
Yukio is a curious and lively young girl who is easily excitable. She laments her families poverty- not because she can't get things, but because she never gets to spend time with her parents and feels abandoned. She is temperamental if she feels ignored by them, which eases into a state of depression.
After being informed of her parents intentions to work on Christmas evening, Yukio angrily told them off after trying to get them to reconsider. She was depressed the following day at school when her friends tried to cheer her up as she remembered how the same thing happened last year. After her friends informed her how similar things happen to her- she suddenly was inspired to hold a party. But after the girls realized none of them had such a place, a classmate who overheard them, Noelle, invited them to her place for her party. While they hadn't spoken to Noelle very much, hearing that she was rich convinced Yukio to take up her offer.
On Christmas Eve the girls showed up at the Kurusu household and were quickly taken by all the decorations and the large home; with Yukio shown displeased as she recalled that they hadn't didn't bother this year. They headed inside and quickly got to looking around until one of Yukio's friends approached a nearby door that Noelle became highly protective of. She claimed it wasn't worth much attention due to only being storage, and while confused by this- Yukio said nothing and they sat down for dinner.
Once she finished she excused herself to the bathroom. When she exited she happened to find Noelle going into the room and curiously trailed behind her to find the girl speaking to someone. She is startled when she sees it is a doll Noelle addresses as Emily, but before she can get closer or leave, she is caught off guard when her friends suddenly show up out of concern she was taking too long. Noelle hid the doll and suggested they go and play games, with Yukio's friends agreeing. But while they played, Yukio was feeling awkward after what she witnessed and watched Noelle curiously, wondering how she could act like nothing was wrong. It was then Noelle's father came home, and watching them, Yukio began to feel saddened again and took off for the restroom once more.
As she shut the living room door behind her, she is surprised to find Emily by her feet. Seeing how dirty she is, Yuki began to rub her off and remarked on how lucky Noelle is to have such caring parents and a happy home. She wishes she could have that.
Later, the girls go to bed. At one point Yukio hears weird sounds and wakes up, but when she doesn't notice anything she assumes it was someone using the restroom and she went back to sleep.
The following morning, Yukio is shocked when Noelle informs her that her friends have left early. She asks why they didn't wake her and Noelle mentions that she told them to go on ahead- so that she could sleep. Yukio is suspicious, but when Noelle's mother suggests she go to wash her face she agrees, still deep in thought. After finishing she checks her phone, still doubtful considering nobody left her any messages, and she rings one of their numbers.
Curiously, she hears the ringtone playing nearby and follows it all the way to the storage room door and steps inside. She is surprised to see the door isn't locked like before, and she notices a bunch of strange scratches on the lock- as if someone was frantically trying to escape. She makes her way around the room as the ringtone plays louder, and soon she kicks something. She realizes the music is playing from it, and to her horror she realizes the corpses of her friends are beneath the large sheet next to the phone. Yukio falls back from alarm as Noelle joins her and brings up how Emily went missing after her friends came up there earlier. She then goes on to say that it's strange she would play with dolls at this age, and she knows that. As she explains how lonely she was in the past, she brings up how she met Emily and how things suddenly improved for her family. But her friends in the past had been so nosy and Emily was very jealous of anybody who got close to her. No matter how hard they tried, people would want to see Emily, and she would kill them.
As Yukio connects the various strange occurrences this past day she wonders if it's possible a doll could be at fault for it. But before she can do anything, Noelle remarks on how sad this situation was- as she considered the girls her friends. Emily joins them, wielding a large kitchen knife and Noelle points out that she still has to deal with Yukio. But to Yukio's shock, she watches as Emily turns on Noelle and lunges at her and her parents, angered by what Noelle said moments ago.
In a flash Yukio gets up and darts out of the home, leaving her items behind as she rushes for her own. Unfortunately, as Yukio gets home she is devastated to discover that neither of her parents are there. Her mother left behind a note, explaining that she had to go into work earlier, reducing Yukio to tears as her stress melts away. She looks up and to her surprise, she finds Emily standing before her, offering her hand in friendship. But as she thinks about what Noelle said, Yukio weeps and accepts her hand.
Several month pass and it is revealed that her family is doing a lot better now. It is theorized that her father got a promotion while her mother became a housewife who baked many cakes for others. However, Yukio vanished, and they recalled how it happened after she went to see her friend around Christmas. As the two women chatting about this wonder where she is, it is revealed that Yukio is happily living with Emily in a brand new home, with a corpse laying before them.