Fumino is a 16-year-old girl who is described as an delinquent in Kumaneko High School, although she is not. She simply interrupts bullies and other bad students in violent ways.
She has a strong personality and sometimes loses her temper. She cares deeply about her brother Teppei. Her parents died in a car accident and so she had to become responsible for her little brother. As a result, she has become more mature and practical than others her age. However, she is terrible at cooking, so she relies on Ojiro to cook for her and her brother.
Even so, she cooked some porridge with some spring onions for Kazuma when he had a high fever. While nursing him with a mask on, he told her that when he was ill, nobody went near him, so they wouldn't get sick too. He also kissed Fumino through the mask, though when he got well, he doesn't remember what he had done.
She once secretly worked in one of Retsu's construction buildings for two weeks (cleaning floors) in order to earn some money to buy Kazuma a birthday present. She bought him a green necktie.
According to chapter 17, Fumino did nothing but sleep in class for the 1st year of school, which causes other students to see her as a bad student. Now she does well in her studies, only slightly poor in English.
Kazuma calls her "Fumino-san". He's very protective of Fumino and doesn't like when other men get too close to her.
Fumino loves Kazuma very much.