Shimura-san is the housekeeper of the Kurata home and, like Rei-kun, she's very much a part of the family. She's a very kind person, so she's always patient with everyone in the house, especially considering that she's the most "normal" member of the family. Even when Mama's dragging Onda around with her little car, Sana's bouncing around rapping, and Rei's panicking about Asako, Shimura-san is always there with a calm, clear head.
Shimura-san appears on most episodes, but her role is a minor one, so she doesn't have much of a background story. The most that's known about her is that she grew up on a farm (from the Piyoko episode) and that she's been with the Kurata family a long time. Naturally, Shimura-san is very attached to everyone, and she seems to be pretty close with Mama. Since she can survive living in the Kurata home, Shimura-san is not really beyond joining the family in their bouts of insanity in her own way sometimes.
