Ayumu Kasuga is a transfer student from Osaka, Japan. Tomo Takino expects her to act like the stereotypical Osakan — loud, like a hillbilly, chose for her the nickname "Osaka", although her behavior could not be more different. She reminisces how people in Osaka consider her "slow" and "spacey", at least compared to the average Osakan, but she lacks the energy or motivation to change. Osaka was the first to ever lose a race against Chiyo Mihama. The nickname sticks so well she is called 'Osaka' by teachers and even in the class roster, to the point that no one (including herself) even remembers her real name (Yomi has a similar problem). In the manga, Osaka mentions that she lived in Kobe when she was in elementary school and was born in Wakayama.