Yukari Sanjo is a twenty-five year old woman who works for Easter as Utau's manager.
Yukari is the lazy, lover-bitter, stingy manager of Utau Tsukiyomi She lives on her own in an apartment and she never cooks for herself or does any chores. Most of the time, she just lays around, drinking cokes, and reading gossip magazines.The only time she seems to be serious and buisness-like, is when she is working as an Easter employee. In fact, Yukari is probably one of the most dedicated Easter employees in the company. She sees nothing wrong in the company's mission, and she helps the most by coming up with genius ideas to obtain X Eggs. Her most popular idea to get X Eggs was to get Utau to chara-change with X Dia before recording a song on a CD. Then, whoever listened to the CD, would have their egg turned into an X Egg.
Since Yukari is Utau's manager, she is very protective of her. She will lecture Utau whenever she gets herself into life treatening situations, and is often worried about Utau if Utau hasn't seen her beloved Ikuto in awhile. She even mentioned how Utau could go into "withdrawls" without Ikuto. To keep this from happening, in Shugo Chara Encore, Yukari assigned Kukai, a rival of Utau's, to hang out with Utau more and keep her mind off of Ikuto. This seemed to work for a little while, but Utau was still sad about not being able to see her beloved brother.
Near the middle of the first season, Kairi, Yukari's cousin; moved in with her because he was ordered by Easter to go under-cover in Seiyo Academy and spy on Amu Hinamori. While he lived with Yukari, Kairi realized how bad she really lived, and therefore, had to cook all of her food and do all of her chores, making his 24/7 outfit an apron. Kairi would lecture her on doing things for herself, but she would never listen to him. When Kairi left, Yukari was sad because she had no one to do her chores or cook for her anymore. To solve this, she has constantly, called Kairi down to Tokyo to do some heavy lifting or tasks for her and Utau so she wouldn't have to do work, and so Kairi would have to stay the night and cook for Yukari.
Yukari quit Easter the same time Utau did, leaving them all alone. Yukari agreed to still being Utau's manager, but without financial support from Easter, they had to settle for performing in the park without being able to charge people for admission. Thankfully, Utau gained her fans back, and they were back on their feet again. They were able to move into an office building and hire a performance team to set up lights and do audio. Yukari and Utau now both have steady jobs and are doing quite well for themselves.
In the final chapter of Shugo Chara, Nikkaido proposed to Yukari and she accepted. The final chapter of Shugo Chara Encore, and the final chapter of the entire series, was based at their wedding.
- Kukai Souma: Yukari and Kukai have gotten to know each other over the many times that Yukari and Utau have called up Kairi and Kukai to do their tasks and heavy lifting for them. After seeing how close Utau and Kukai were, Yukari told Kukai about how depressed Utau was about not being able to see Ikuto, and how she wanted him to hang out with Utau more in order to cheer her up. It worked for a little while, but Utau soon became sad again after that because she still couldn't see Ikuto.
- Kairi Sanjo: Kairi is Yukari's cousin, and constantly uses him for her bidding. However, they do have a close relationship, and they do miss each other when Kairi has to leave Tokyo.
- Utau Tsukiyomi: Utau and Yukari are very close, and Yukari is very protective of her. Yukari even lectured her one time for risking her life by saving Yukari from falling from a helicopter mid-flight. They quit Easter together and went off on their own to start their own recording company. Even without the financial help of Easter, they soon got back on their feet and are now working together successfully.
- Kukai Souma: Kukai, along with Kairi, is constantly called over to Yukari Studios to help with some of the heavy lifting, because of this, Yukari has gotten to know Kukai. In Shugo Chara Encore chapter 1, Yukari sat down to lunch with Kukai and explained to him that Utau was feeling depressed lately because she wasn't able to see Ikuto. Yukari then told Kukai that she wanted him to hang out with Utau so she would be distracted and not think about Ikuto so much. Kukai tried to explain to her that they really weren't that close and that they only ate ramen together one time, but Yukari didn't listen to him and forced him to hang out with Utau for the next week.
Yuu Nikkaido: Yukari and Nikkaido were revealed to have a relationship before the series started, but it ended horribly, which caused Yukari to be bitter against men, and love in general. Because they have to work together, things can get very tense and very awkward. Even though Yukari was in love with Nikkaido, she used every chance she got to tell him how stupid he looked or how lame he was. Even though she was still in love with him, she used these angry advances as a way to hide it. However, Nikkaido saw right through her, and knows that Yukari is still in love with him.
In the second season, Nikkaido is constantly seen going over to the recording office to visit Yukari on the job. Once, while Yukari was sick and sleeping, she dreamed that she was touching Nikkaido's face and telling him how beautiful he was. But when she woke up, she saw that he really was there, she was really touching his face, and that she really said that to him. However, she quickly blammed her cold for the "crazy" things she said. Her crush on him continued even more when she forced him to go to a "shout-out-your-love" contest. Even though she said she only wanted to do it so she could win the heart shaped hula-hoop (for Utau's dance practice), she really entered because she wanted to hear him say that he loved her. Instead, he accidently pissed Yukari off, and she yelled at him to apologize. So instead of saying "I LOVE YOU!!!", he screamed out "I'M SORRY!!!" in front of the crowd, which actually earned them the heart-shaped hula-hoop.
In the last chapter of Shugo Chara, after Nikkaido and Yukari had a huge fight, the whole gang pulled off an event in which Utau sung one of her new songs before Nikkaido purposed to Yukari, telling her that he loved her. Yukari blushed and agreed to marry him.