Ushio is the best friend of Sumika, the protagonist, and always has been —oblivious to Sumika’s feelings for her (though she does at one point recognize that Sumika is in love, and feels guilty, even, for not realizing it sooner; she just doesn’t understand that it’s her Sumika feels that way with). Ushio has made it clear that Sumika isn’t her type; Ushio’s “type” consists of —cute— girl; small and feminine and innocently curious, the kind one would want to protect, and Sumika far from falls into that category.
Ushio is constantly falling for girls like that —only to find her crushes unrequited again and again, leaving Sumika to end up consoling her when her heart breaks. She wishes just once that she could find a girl who would return her feelings. Her spirits are lifted, however, upon a lesbian couple in her class forming the Girls Club for women interested in women with her and Sumika (and her straight friend Kiyori, who goes along with the idea due to make the necessary number of people needed to form a club).
Ushio lives only with her brother (a yuri novelist, ironically enough); her parents, she says, are “gone”, her place a mess because of this. She seems to have gotten over what happened, for the most part, in the story.