Kosaki Onodera is a kind and quiet classmate of Raku Ichijo, Kosaki is caring and friendly. She works with her mother at a confectionery shop, though her cooking skills are poor; however, her food often looks visually appealing. She is trying to learn how to swim. Kosaki is in love with Raku but cannot confess her feelings due to her shyness. Her friend, Ruri, constantly tries to bring them closer, which often leads to awkward situations between Kosaki and Raku. She also has a younger sister named Haru.