A second-year middle school second year, Ayumi is one day asked out by Misao Zaitsu. Though she claimed she would accept any offer, she is consistently unsettled by Zaitsu's monstrous appearance; however, she shows she can be somewhat caring as well as crafty. She is 152cm (4'9") tall and runs the second fastest in her class.

She's also unusually strong for her size and build, as demonstrated when she knocked out Misao with a single kick. She falls in love with Misao's younger brother Mamoru after he carries her to the infirmary. At the end, she is trying to decide between the two Zaitsu brothers, whether to choose the one who likes her (Misao) or the one she likes (Mamoru).
She shares a strong resemblance to Chinami Hashimoto, a character from another of Kawashita's work, Ichigo 100%.