She is shown to have great annoyance at Saya for being too soft and always helping people (the reason she comes to school late) which causes her to get angry. But she is still kind despite her hot headed nature. In reality, Yūka is actually a cold woman who will do anything to achieve her goals and shows little value toward human life.
She has the appearance of a tall teenager with fair skin, dark eyes and nude lipstick. Yūka sports chin length black hair with a fringe cut on the right side. On terms of clothes, Yūka mostly wears her school uniform.
At the end of the series, after the deaths of the Main Cast, it is revealed that Yūka is actually a woman in her mid to late twenties.
In "Blood-C: The Last Dark" movie, Yūka now appears more her age: she wears a formal suit of a grey blazer with a turquoise blouse underneath, a dark grey pencil skirt, black hose, and blue heels. She also wears a necklace and red lipstick.
PlotYuuka is first seen when Saya comes into the classroom and states that she made it on time. Saya states that it had some trash on the road but she put it in the trash area so it would be fine. Yuuka yells at her asking how she could be such a softy. The twins then start to tease her saying she was scary and she acted like an overprotective mom making her more angry (in a comical fasion). They are interupted by Itsuki who tells them that the teacher would be coming soon and that they should continue their little routine later. After P.E, Yuuka asks Saya if she was always good at sports because she was so good at it. Saya says that her mother was dead and her father was almost always busy with the shrine so it wasn't ever like that. She then goes on to explain her mom's death and how Fumito gave her boxed lunches to cheer her up. Yuuka then states that Fumito and her father must be good people and Saya with a smile says yes. After school she is seen with the twins watching Saya leave the classroom and she turns around and says bye. The next day she is seen when Saya started to talk about the dog she saw on her way to school. Yuuka said that it must have been abandoned but Saya disagreed saying it was too bold.They are again interupted by Itsuki and Saya tells him good morning. He says that she should call him by his name instead and Saya
says that she could call him class rep Tomofusa and he says that that wasn't what he meant. At lunch time Saya, Nene, Nono & Yuuka were eating their lunch together (a plan set up by Itsuki to get closer to Saya) until Saya saw Tokizane and went to greet him. After she finished talking to him, Yuuka told Saya to hurry up because they were almost finished eating.The next day, Yuuka is seen with Nene and Nono as they run up to Saya and asked her if they could go somewhere. Yuuka said that their wasn't anything interesting in the town and they both said she was mean. Saya then notices Itsuki and he comes over to ask her what she wanted and Saya asked him what was the name of the place he said had good cakes. After he said that he was talking about Cafe Guimauve but stated that he was glad she refused to go last time.Yuuka asks why and Itsuki says that he would have looked like an idiot because he acted like he knew the place and she was a reguler customer there. When they desided they were going, Yuuka told Itsuki that sending Saya to the cafe may have worked and he just laughs. They walk down the road and stop when Nene and Nono started to complain about how boring the town was. Saya then comments on how they talk good simultaneously and Yuuka says that they're like a comedy routine. Nene and Nono said that she could have said they acted like an idol or a band but Saya says she doesn't know what they were talking about since she doesn't have a TV (which everyone expressed shock at). At the cafe Yuuka commented that she doesn't really like cake but the one she's eating is good. After Itsuki said that he liked to cook but says that Saya would probably take it the wrong way, Yuuka is seen looking at Saya with Nono. When Saya asked what they were looking at Yuuka just sighs aher on the back. Soon after a policeman came and told them to go home before dark since the Nightingale Bakery's owner went missing and after they left leaving Saya
The next day she is seen walking to the usual spot to eat lunch with everyone else. After Nono states that the baker must have just gotten tired of the countryside and ran away, Yuuka asked if it was still called 'running away' even when your an adult. Nene asked what else you would call it and Itsuki said it wthey replied that that was the correct answer. Yuuka along with everyone else watch as Saya chases after the he's been seeing recently and later Nene asked where she went but Yuuka replied that she doesn't even know.
In episode 9, she is killed among several of Saya's classmates by the crab-like Elder Bairn. As for Nene and Nono, their deaths were faked due to the fact that they were both part of the main cast. In the last episode, Yuuko was the only survivor of the main cast who was rewarded by Fumito, who made her wish to become the next governor of Tokyo come true.
They were close friends. Sometimes she would scold her for always being so late, or just on time. They appear to have a strong bond within the manga, and Saya cried apposedly died in her arms.
The twins often insulted her calling her scary like their mom, however they were friends but as they were all in the Main Cast it is unknown how they really felt about each other.