Yumi Shimizu is the eldest daughter of Kasumi Shimizu.
As the eldest daughter of the Shimizu family, Yumi was expected to inherit the Ryokan Hiei. However, she felt so trapped with the idea that she left to run a bento stand in the city instead.
Bess and George meet Yumi in Kyoto in 2010 and become good friends with her. Knowing that she grew up at the Ryokan Hiei, where Nancy is staying, they encourage Nancy to meet her. Taking trains to Matsue, Nancy sees her working a bento booth and as soon as Yumi discovers she's friends with Bess and George, she gets the super-sleuth to work alongside her. Yumi warms up to Nancy very quickly and within their first conversation she gives Nancy her phone number and a key to her apartment with the orders to retrieve her extra bento boxes.
Nancy can always make bento boxes with Yumi and can even trade phone charms with her, but she can't get Yumi to talk about her mother or the hauntings at the ryokan. Even though Yumi seems to resent the place and wants nothing to do with it, she is still protective of its secrets and will refuse to talk to Nancy if she gets too pushy. Despite Nancy's determination to know what happened to Kasumi, or perhaps because of that determination, Yumi sends her purikura photos of her, Bess, George, and Rentaro. Hidden within those colorful pictures is a code that opens a little froggy safe in her apartment, revealing her half of Kasumi's nonogram numbers. Even though she can be very prickly when it comes to the Ryokan Hiei, she appears to want Nancy to help her family.
Yumi and Miwako are not close and never really have been, but after Nancy uses the nonogram numbers and discovers Kasumi's final letter stating her wishes that the girls stop fighting and work together instead and that neither girl has to run the ryokan, their previous animosity vanishes and allows the girls to form a better relationship.
- Yumi has a blog at http://yumi-shimizu.blogspot.com/.
- When Yumi was only fifteen, she discovered her mother's body drowned in one of the ryokan baths.
- Yumi makes her own clothes, all of them pink and Lolita-style. She seems very fond of all things she considers cute and adorable.
- Yumi talks very fast and is considered bossy by many people. Rentaro says being bossy is her way of saying that she is the boss, do what she says. Miwako, who has thought the matter over, declares her to be "bratty and manipulative". Their mother described her eldest daughter as a "free-spirit".
- Takae thinks Yumi's personality is very like Kasumi's when she was her age.
- Takae taught Yumi how to cook.
- As children, she and Rentaro used to sneak on the trains without supervision and travel around Kyoto, landing them both in a lot of trouble every time.
- "Absolutely not. Who's asking? It might be. Are you going to order? What's your agenda here, stranger?"
- "Once you know how to make a good bento box, you pretty much got the whole world figured out."
- "You want to go to the past? Get a time machine. I'm not one for living in the past. Have you ever read a history book? The past is where we keep all of the terrible things that have happened."
- "Get a job, phone charm! It probably won't."
- "Don't get all everyone else on me here."
- "Hello! Not in! Bye bye!"