Sumino Hana

She is the same age as the main character and is in the same class. She tends to miss school because of illness and weakness, and she adores the protagonist, who spends more time with her than her parents, who both work.

She does not hide her affection for her brother, but rather routinely makes bold remarks to him, even to the point of sexual harassment.

She is a firm person who sometimes gives him advice like a big sister, but she also has a lot of childish behavior, such as being selfish like a mischievous child.