Kumin is a carefree-girl who is a year above Yuuta and the others. She adores any chuunibyous.
Kumin has dark purple eyes and short black hair. She has very fair skin and a small mole on her right breast. She is very friendly and can blend in with others well. She loves sleep so much that she brings a pillow with her almost everywhere she goes. After getting along with Rikka and Sanae Dekomori, she tries to understand their delusions and always supports their activities. She is an airhead girl who is very pure. She likes to touch Makoto Isshiki’s bald head, as she is curious. She also enjoys scenes where fighting and horror occurs.
Kumin lives with her family and went overseas for her dad’s work. She got homeschooled until high school. Due to being overprotected by her family, she has an old-fashioned ladylike ethics.