Izumi's mother.
She is a writer and has a very estranged relationship with her daughter who she treats more like a peer rather than a child. Shimako does not mind that Izumi calls her by her first name, and they have a rather close bond. Izumi comes to her often for advice. She laments that Izumi is just as bad in the kitchen as she is, and so they resort to buying their food pre-cooked and are both masters of the microwave dinner.
Shimako thinks her daughter is an idiot. Despite this, she cares for her very much and lets her do what she whatever she wants.
[This character appears in the chapter "A Lunch Made with Love".]

Related manga:

Kawaii Anata Manga, 2007
Love Letter Manga, 2008